Use LOCATION_MODE to control location

Completely deprecate LOCATION_PROVIDERS_ALLOWED (but still support it).
Adds additional locking and @GuardedBy annotations where appropriate,
and some minor code cleanup is copied from previous CLs.

Bug: 118885128
Test: Manual + CTS
Change-Id: I3c0b4b2354a4c2b6a120fc467af60cb3409dd671

• api/system-current.txt[diff]
• config/hiddenapi-greylist.txt[diff]
• core/java/android/provider/Settings.java[diff]
• location/java/android/location/ILocationManager.aidl[diff]
• location/java/android/location/LocationManager.java[diff]
• services/core/java/com/android/server/LocationManagerService.java[diff]
• services/core/java/com/android/server/location/AbstractLocationProvider.java[diff]
• services/core/java/com/android/server/location/GnssLocationProvider.java[diff]
• services/core/java/com/android/server/location/LocationProviderProxy.java[diff]
• services/core/java/com/android/server/location/MockProvider.java[diff]
• services/core/java/com/android/server/location/PassiveProvider.java[diff]
• services/core/java/com/android/server/pm/UserRestrictionsUtils.java[diff]