Import Accompanist Pager

This pager is need to show independent content in the two pages,
otherwise there will be some issues.

FlingBehavior of pager is TODO because it currently need extra external
dependency.

Also created SettingsScaffold to work with pager.

Bug: 235727273
Test: Manual with Gallery App
Change-Id: If3c229457bbe0aac4c8139d02443f8f13be22dbc