Add overlays for nav bar interaction mode.

- Add config for nav bar interaction mode
- Add overlay packages for overriding the nav bar interaction mode
- Migrate existing swipe up setting into the resource overlay
  P2 P->Q:
    def/off -> 3 button overlay enabled (from default)
    set on  -> 2 button overlay enabled (from setting)
  P3 (default on):
    def (setting not exposed) -> 2 button overlay enabled (from default)

Bug: 127366543
Test: adb shell cmd overlay dump

Change-Id: I75590f81d9dd6a017776e0a34c295575bfe1bf2a