fix(segment): add activated class directly to segment button (#20400)

this gets around a bug with Safari where the ::slotted css selector was not working properly

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

@@ -140,6 +140,10 @@
 // Segment: States
 // --------------------------------------------------
 
+:host(.segment-button-activated) {
+  --indicator-transform: scale(0.95);
+}
+
 :host(.ion-focused) .button-native {
   opacity: $segment-button-ios-opacity-focused;
 }

core/src/components/segment-button/segment-button.tsx

@@ -23,9 +23,6 @@ export class SegmentButton implements ComponentInterface, ButtonInterface {
 
   @Element() el!: HTMLElement;
 
-  /**
-   * If `true`, the segment button is selected.
-   */
   @State() checked = false;
 
   /**