Remove GameManagerService from Wear

This change removes the GameManagerService from Wear devices.
Consequently, the GameManager client API will have no use for Wear
devices. Thus, GameManager is now also allowed to be not published by
Wear devices.

To avoid affecting existing apps that may be interacting with a
GameManager instance, we are guarding the absence of GameManager with an
app target SDK check. Apps that target an SDK prior to this change will
still be able to get a GameManager instance, but it will be no-op.

The public documentation has also been updated to reflect these new
changes.

Bug: 340929737
Test: atest CtsGameManagerTestCases CtsGameFrameRateTestCases
GameManagerTests
Flag:  android.server.remove_game_manager_service_from_wear

Change-Id: Id5affc748a97b7204ebf4c61a198ebd87d757a2a