Add @PermissionMethod annotation

For use by static analysis, @PermissionMethod documents
the methods in the platform that perform permission "checks" (e.g.
context.enforceCallingOrSelfPermission).

Said methods either return in int of type @PermissionResult, or return
void and potentially throw a SecurityException.

There are currently two platform lints that care about this information.
ManualPermissionCheckDetector and PackageVisibilityDetector.

See: go/enforcepermission-migration-design
Bug: 247537842
Test: Tested manually, ultimately will be tested in presubmit (atest
AndroidFrameworkLintCheckerTest, see b/240445172)

Change-Id: Ia21ba748eab37b532b591edb2599bb78ea0c8c9d