Allow screenOffScan to holders of MEDIA_CONTENT_CONTROL

Before this change, only holders of MEDIA_ROUTING_CONTROL are allowed to
perform screen off scans. But MEDIA_ROUTING_CONTROL is an appopp
permission that's not available to privileged apps via pre-granting.

MEDIA_CONTENT_CONTROL is a privileged permission that's pre-grantable.

This is a cherrypick of 49da9beb.

Bug: b/352401364
Test: atest CtsMediaBetterTogetherTestCases CtsMediaHostTestCases
Flag: com.android.media.flags.enable_full_scan_with_media_content_control
(cherry picked from https://googleplex-android-review.googlesource.com/q/commit:225bb17aacbd7f887497515dd8a28f2b7e71e762)
Merged-In: I1118bf56a03977ddcfdf37c21f14f532ff3ad0d5
Change-Id: I1118bf56a03977ddcfdf37c21f14f532ff3ad0d5