fix(angular): remove form control side effects (#28359)

Issue number: resolves #28358

---------

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issue. -->

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etc). Submit multiple pull requests if needed. -->

## What is the current behavior?
<!-- Please describe the current behavior that you are modifying. -->


28f2ec9c62
exposed a (possible) `ng-packagr` bug where the form control components
were being re-assigned, which breaks treeshaking. These components were
considered side effects and were always being pulled into the bundle.

This resulted in a higher than expected bundle size. This issue appears
to be caused by using 2 decorators **and** referring to the class in
`useExisting` (for providers). Doing just one of these does not
reproduce the issue.

The compiled output looks something like this:

```typescript
let IonToggle = IonToggle_1 = /*@__PURE__*/ class IonToggle extends ValueAccessor {
    constructor(c, r, z, injector) {
        super(injector, r);
        this.z = z;
        c.detach();
        this.el = r.nativeElement;
        proxyOutputs(this, this.el, ['ionChange', 'ionFocus', 'ionBlur']);
    }
    writeValue(value) {
        this.elementRef.nativeElement.checked = this.lastValue = value;
        setIonicClasses(this.elementRef);
    }
    handleIonChange(el) {
        this.handleValueChange(el, el.checked);
    }
};
/** @nocollapse */ IonToggle.ɵfac = i0.ɵɵngDeclareFactory({ minVersion: "12.0.0", version: "14.2.12", ngImport: i0, type: IonToggle, deps: [{ token: i0.ChangeDetectorRef }, { token: i0.ElementRef }, { token: i0.NgZone }, { token: i0.Injector }], target: i0.ɵɵFactoryTarget.Component });
/** @nocollapse */ IonToggle.ɵcmp = i0.ɵɵngDeclareComponent({ minVersion: "14.0.0", version: "14.2.12", type: IonToggle, isStandalone: true, selector: "ion-toggle", inputs: { checked: "checked", color: "color", disabled: "disabled", enableOnOffLabels: "enableOnOffLabels", justify: "justify", labelPlacement: "labelPlacement", legacy: "legacy", mode: "mode", name: "name", value: "value" }, host: { listeners: { "ionChange": "handleIonChange($event.target)" } }, providers: [
        {
            provide: NG_VALUE_ACCESSOR,
            useExisting: IonToggle_1,
            multi: true,
        },
    ], usesInheritance: true, ngImport: i0, template: '<ng-content></ng-content>', isInline: true, changeDetection: i0.ChangeDetectionStrategy.OnPush });
IonToggle = IonToggle_1 = __decorate([
    ProxyCmp({
        defineCustomElementFn: defineCustomElement$1i,
        inputs: TOGGLE_INPUTS,
    })
], IonToggle);
```

## What is the new behavior?
<!-- Please describe the behavior or changes that are being added by
this PR. -->

- Removed the `ProxyCmp` usage in favor of manually calling proxyInputs
and proxyMethods.
-  Also saw that select was missing a form control test, so I added one

The compiled code now looks something like this:

```typescript
class IonToggle extends ValueAccessor {
    constructor(c, r, z, injector) {
        super(injector, r);
        this.z = z;
        defineCustomElement$1i();
        proxyInputs(IonToggle, TOGGLE_INPUTS);
        c.detach();
        this.el = r.nativeElement;
        proxyOutputs(this, this.el, ['ionChange', 'ionFocus', 'ionBlur']);
    }
    writeValue(value) {
        this.elementRef.nativeElement.checked = this.lastValue = value;
        setIonicClasses(this.elementRef);
    }
    handleIonChange(el) {
        this.handleValueChange(el, el.checked);
    }
}
/** @nocollapse */ IonToggle.ɵfac = i0.ɵɵngDeclareFactory({ minVersion: "12.0.0", version: "14.2.12", ngImport: i0, type: IonToggle, deps: [{ token: i0.ChangeDetectorRef }, { token: i0.ElementRef }, { token: i0.NgZone }, { token: i0.Injector }], target: i0.ɵɵFactoryTarget.Component });
/** @nocollapse */ IonToggle.ɵcmp = i0.ɵɵngDeclareComponent({ minVersion: "14.0.0", version: "14.2.12", type: IonToggle, isStandalone: true, selector: "ion-toggle", inputs: { checked: "checked", color: "color", disabled: "disabled", enableOnOffLabels: "enableOnOffLabels", justify: "justify", labelPlacement: "labelPlacement", legacy: "legacy", mode: "mode", name: "name", value: "value" }, host: { listeners: { "ionChange": "handleIonChange($event.target)" } }, providers: [
        {
            provide: NG_VALUE_ACCESSOR,
            useExisting: IonToggle,
            multi: true,
        },
    ], usesInheritance: true, ngImport: i0, template: '<ng-content></ng-content>', isInline: true, changeDetection: i0.ChangeDetectionStrategy.OnPush });
```

## Does this introduce a breaking change?

- [ ] Yes
- [x] No

<!-- If this introduces a breaking change, please describe the impact
and migration path for existing applications below. -->


## Other information

<!-- Any other information that is important to this PR such as
screenshots of how the component looks before and after the change. -->

Ryan provided some context on a related Stencil bug where doing
reassignments broke treeshaking in Webpack. While the source of this bug
is not Stencil, understanding the Stencil bug helped me better
understand this issue:

https://github.com/ionic-team/stencil/issues/3191
https://github.com/ionic-team/stencil/pull/3248
https://github.com/ionic-team/stencil/pull/4188 (fixes an issue
introduced in the above stencil PR)

Dev build: `7.5.1-dev.11697480817.10fa2601`

packages/angular/standalone/src/directives/checkbox.ts

@@ -8,12 +8,25 @@ import {
   Injector,
   NgZone,
 } from '@angular/core';
+import type { OnInit } from '@angular/core';
 import { NG_VALUE_ACCESSOR } from '@angular/forms';
 import { ValueAccessor, setIonicClasses } from '@ionic/angular/common';
 import type { CheckboxChangeEventDetail, Components } from '@ionic/core/components';
 import { defineCustomElement } from '@ionic/core/components/ion-checkbox.js';
 
-import { ProxyCmp, proxyOutputs } from './angular-component-lib/utils';
+/**
+ * Value accessor components should not use ProxyCmp
+ * and should call defineCustomElement and proxyInputs
+ * manually instead. Using both the @ProxyCmp and @Component
+ * decorators and useExisting (where useExisting refers to the
+ * class) causes ng-packagr to output multiple component variables
+ * which breaks treeshaking.
+ * For example, the following would be generated:
+ * let IonCheckbox = IonCheckbox_1 = class IonCheckbox extends ValueAccessor {
+ * Instead, we want only want the class generated:
+ * class IonCheckbox extends ValueAccessor {
+ */
+import { proxyInputs, proxyOutputs } from './angular-component-lib/utils';
 
 const CHECKBOX_INPUTS = [
   'checked',
@@ -28,10 +41,6 @@ const CHECKBOX_INPUTS = [
   'value',
 ];
 
-@ProxyCmp({
-  defineCustomElementFn: defineCustomElement,
-  inputs: CHECKBOX_INPUTS,
-})
 @Component({
   selector: 'ion-checkbox',
   changeDetection: ChangeDetectionStrategy.OnPush,
@@ -47,15 +56,25 @@ const CHECKBOX_INPUTS = [
   ],
   standalone: true,
 })
-export class IonCheckbox extends ValueAccessor {
+export class IonCheckbox extends ValueAccessor implements OnInit {
   protected el: HTMLElement;
   constructor(c: ChangeDetectorRef, r: ElementRef, protected z: NgZone, injector: Injector) {
     super(injector, r);
+    defineCustomElement();
     c.detach();
     this.el = r.nativeElement;
     proxyOutputs(this, this.el, ['ionChange', 'ionFocus', 'ionBlur']);
   }
 
+  ngOnInit(): void {
+    /**
+     * Data-bound input properties are set
+     * by Angular after the constructor, so
+     * we need to run the proxy in ngOnInit.
+     */
+    proxyInputs(IonCheckbox, CHECKBOX_INPUTS);
+  }
+
   writeValue(value: boolean): void {
     this.elementRef.nativeElement.checked = this.lastValue = value;
     setIonicClasses(this.elementRef);