feat(segment): add missing focus state on segment for Ionic theme (#30074)

Issue number: internal

---------

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

This is part of a bigger task to add focus styles on all components that
need them on Ionic Theme. A separate PR will be done for each component.

- Added new focus styles for segment on Ionic theme.
- Added new state test and snapshots.
- UI is slightly different from Figma, but t was discussed and aligned
with UX/UI.

## 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. -->

- [Ionic Segment
Focus](https://ionic-framework-ixz97yf70-ionic1.vercel.app/src/components/segment/test/a11y?ionic:theme=ionic)

Author: BenOsodrac

core/src/components/segment-button/segment-button.ionic.scss

@@ -79,6 +79,13 @@
   color: var(--color-disabled);
 }
 
+// Segment Button: Focused
+// --------------------------------------------------
+
+:host(.ion-focused) .button-inner {
+  @include globals.focused-state();
+}
+
 // Segment Button: Indicator
 // --------------------------------------------------
 

core/src/components/segment/test/states/segment.e2e.ts

@@ -0,0 +1,29 @@
+import { expect } from '@playwright/test';
+import { configs, test } from '@utils/test/playwright';
+
+configs({ modes: ['ionic-md'], directions: ['ltr'] }).forEach(({ title, screenshot, config }) => {
+  test.describe(title('segment: states'), () => {
+    test('should render focused segment correctly', async ({ page }) => {
+      await page.setContent(
+        `
+        <ion-segment value="2">
+            <ion-segment-button value="1">
+            <ion-label>Bookmarks</ion-label>
+            </ion-segment-button>
+            <ion-segment-button class="ion-focused" value="2">
+            <ion-label>Reading List</ion-label>
+            </ion-segment-button>
+            <ion-segment-button value="3">
+            <ion-label>Shared Links</ion-label>
+            </ion-segment-button>
+        </ion-segment>
+        `,
+        config
+      );
+
+      const segment = page.locator('ion-segment');
+
+      await expect(segment).toHaveScreenshot(screenshot(`segment-focused`));
+    });
+  });
+});