Revert "Revert "Add remote callbacks for persistent vr mode""

This reverts commit 2abf1c60cc2fc6ec9bc590cb35e94581ecf93c2e.

We need the ability to register remote callbacks for persistent vr mode,
so vr flinger can register for persistent vr mode events.

Bug: 35885165

Test: Manually confirmed vr flinger can register and receive persistent
vr mode events.

Change-Id: I7713c4c8acae9a369fd0c06695ef712fddd12be8
8 files changed