fix(action-sheet): remove the height shift on press and update iOS design (#16862)

This changes the border into a linear gradient background image which allows us to avoid the height decrease on press and have the same border as the background color when pressed.

- merges all action sheet tests to the basic directory (except standalone, translucent), references #16715
- removes the height shift on press, fixes #16790
- fixes the cancel button on iOS so it is `#ffffff` by default
- gets the look of the action sheet closer to native for iOS
- only applies the translucent and backdrop filter if it is supported by the browser (chrome will not show transparent anymore)
- updates documentation to describe when translucent will show up
- adds documentation on how to use screenshot tests

core/src/components.d.ts

@@ -156,7 +156,7 @@ export namespace Components {
     */
     'subHeader'?: string;
     /**
-    * If `true`, the action sheet will be translucent.
+    * If `true`, the action sheet will be translucent. Only applies when the mode is `"ios"` and the device supports backdrop-filter.
     */
     'translucent': boolean;
   }
@@ -218,7 +218,7 @@ export namespace Components {
     */
     'subHeader'?: string;
     /**
-    * If `true`, the action sheet will be translucent.
+    * If `true`, the action sheet will be translucent. Only applies when the mode is `"ios"` and the device supports backdrop-filter.
     */
     'translucent'?: boolean;
   }