feat(angular): ship Ionic components as Angular standalone components (#28311)

Issue number: N/A

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issue. -->

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

**1. Bundle Size Reductions**

All Ionic UI components and Ionicons are added to the final bundle of an
Ionic Angular application. This is because all components and icons are
lazily loaded as needed. This prevents the compiler from properly tree
shaking applications. This does not cause all components and icons to be
loaded on application start, but it does increase the size of the final
app output that all users need to download.

**Related Issues**

https://github.com/ionic-team/ionicons/issues/910

https://github.com/ionic-team/ionicons/issues/536

https://github.com/ionic-team/ionic-framework/issues/27280

https://github.com/ionic-team/ionic-framework/issues/24352

**2. Standalone Component Support**

Standalone Components are a stable API as of Angular 15. The Ionic
starter apps on the CLI have NgModule and Standalone options, but all of
the Ionic components are still lazily/dynamically loaded using
`IonicModule`. Standalone components in Ionic also enable support for
new Angular features such as bundling with ESBuild instead of Webpack.
ESBuild does not work in Ionic Angular right now because components
cannot be statically analyzed since they are dynamically imported.

We added preliminary support for standalone components in Ionic v6.3.0.
This enabled developers to use their own custom standalone components
when routing with `ion-router-outlet`. However, we did not ship
standalone components for Ionic's UI components.

**Related Issues**

https://github.com/ionic-team/ionic-framework/issues/25404

https://github.com/ionic-team/ionic-framework/issues/27251

https://github.com/ionic-team/ionic-framework/issues/27387

**3. Faster Component Load Times**

Since Ionic Angular components are lazily loaded, they also need to be
hydrated. However, this hydration does not happen immediately which
prevents components from being usable for multiple frames.

**Related Issues**

https://github.com/ionic-team/ionic-framework/issues/24352

https://github.com/ionic-team/ionic-framework/issues/26474

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

- Ionic components and directives are accessible as Angular standalone
components/directives

## 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. -->

Associated documentation branch:
https://github.com/ionic-team/ionic-docs/tree/feature-7.5

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Co-authored-by: Maria Hutt <thetaPC@users.noreply.github.com>
Co-authored-by: Sean Perkins <sean@ionic.io>
Co-authored-by: Amanda Johnston <90629384+amandaejohnston@users.noreply.github.com>
Co-authored-by: Maria Hutt <maria@ionic.io>
Co-authored-by: Sean Perkins <13732623+sean-perkins@users.noreply.github.com>

packages/angular/test/README.md

@@ -70,6 +70,14 @@ If you want to add a version-specific change, add the change inside of the appro
 
 If you need to add E2E tests that are only run on a specific version of the JS Framework, replicate the `VersionTest` component on each partial application. This ensures that tests for framework version X do not get run for framework version Y.
 
+### Testing Lazy Loaded Ionic Components
+
+Tests for lazy loaded Ionic UI components should only be added under the `/lazy` route. This ensures the `IonicModule` is added.
+
+### Testing Standalone Ionic Components
+
+Tests for standalone Ionic UI components should only be added under the `/standalone` route. This allows for an isolated environment where the lazy loaded `IonicModule` is not initialized. The standalone components use Stencil's custom element bundle instead of the lazy loaded bundle. If `IonicModule` is initialized then the Stencil components will fall back to using the lazy loaded implementation instead of the custom elements bundle implementation.
+
 ## Adding New Test Apps
 
 As we add support for new versions of Angular, we will also need to update this directory to test against new applications. The following steps can serve as a guide for adding new apps: