Support RTL layouts in STL

This CL adds support for RTL layouts by introducing
SwipeDirection.{Start,End} and Edge.{Start.End}. These are resolved
using the current LayoutDirection when building the user actions map.

I decided to introduce a Resolved subclass in UserAction, SwipeDirection
and SwipeSource so that resolving a user action before using it is
enforced by the compiler.

Bug: 320786721
Test: atest SwipeToSceneTest
Flag: com.android.systemui.scene_container
Change-Id: I028ee755b9be67594a9abdc3127307ba789a07e4