Enforce MediaButtonReceiver ComponentName belongs to app

Adds check that enforces ComponentName's package belongs to calling app.
This avoids privileged execution of arbitrary code through media button
events.

This is a partial revert revert of ag/19338169.

Bug: 238177121
Test: atest CtsMediaBetterTogetherTestCases
Change-Id: I4aba866a9758366175ea4af0d434729ad98fa48d
(cherry picked from commit 1b2fa248)
Merged-In: I4aba866a9758366175ea4af0d434729ad98fa48d