Add a new "appPredictor" protection flag.

Permissions that have the new apppredictor protection flag will
be granted to the app predictor app, which is AiAi for Pixels.

The MANAGE_APP_PREDICTIONS permission is updated to use the
app predictor flag.

App Predictor for Pixels already set in ag/6019430.
Some one-off handling for app predictor already added in
ag/6025266 and ag/6025267. This cl adds the appPredictor flag.

Test: Tested manually that it worked.
Test: atest CtsPermission2TestCases:PermissionPolicyTest
Bug:123599542

Change-Id: I0550930f78fdb57eea8680762c9b313a330968b6