fix(segment): setting value via binding updates button state (#28837)

Issue number: resolves #28816

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## What is the current behavior?
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The value is set on Segment asynchronously when binding it in Angular.
However, the timing works out such that the value changes after
`connectedCallback` is fired but before any Stencil Watchers are
configured. As a result, our `value` property watcher does not fire
which causes `ionSelect` to not be emitted. Segment Buttons rely on this
event to know when to update their state (if the value changes such that
a segment button is now selected). This results in a checked segment
button not appearing checked.

This is similar to other issues that have been fixed:

https://github.com/ionic-team/ionic-framework/pull/28510
https://github.com/ionic-team/ionic-framework/pull/28488
https://github.com/ionic-team/ionic-framework/pull/28526

## What is the new behavior?
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this PR. -->

- Segment now emits `ionSelect` on `componentDidLoad` so that any
descendant segment buttons can update correctly.

## Does this introduce a breaking change?

- [ ] Yes
- [x] No

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## Other information

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screenshots of how the component looks before and after the change. -->

Dev build: `7.6.5-dev.11705415448.16878103`

This is a timing issue with Stencil, so I am unable to write a reliable
automated test. Reviewers should test the dev build in the repro
provided in the linked issue.

core/src/components/segment/segment.tsx

@@ -140,6 +140,14 @@ export class Segment implements ComponentInterface {
   async componentDidLoad() {
     this.setCheckedClasses();
 
+    /**
+     * If the value changes before watchers
+     * are setup, then the ionSelect watch callback
+     * will not fire. As a result, we manually
+     * fire this event when Select is loaded.
+     */
+    this.ionSelect.emit({ value: this.value });
+
     /**
      * We need to wait for the buttons to all be rendered
      * before we can scroll.