[Accessibility APIs] Add Expansion API

This CL will add the implementation for the API defined here:
go/aria-expanded-collapsed-android-api-change-design-proposal

Flag: android.view.accessibility.a11y_expansion_state_api
Test: CQ + new Tests
Bug: 362782466
Change-Id: Ibb53e25539a68e614cbf712035241a1e8f2e67f4