Move mPermissions from package settings

Create a settings class only for use with permissions. It's
subservient [and should only be accessed directly by] package
settings or the permission manager. The rest of the permission
related data needs to be moved to permission settings. At
which point we can start pulling the permission methods out of
the package manager service and into the permission manager.

We still have a somewhat tight relationship between package
manager and the permission manager. It's unclear how far we need
to separate them and if relying entirely on an internal
interface is sufficient.

Bug: 63539144
Test: Manual. Builds and runs
Test: cts-tradefed run commandAndExit cts-dev -m CtsAppSecurityHostTestCases -t android.appsecurity.cts.PermissionsHostTest
Test: cts-tradefed run commandAndExit cts-dev -m CtsPermissionTestCases
Test: cts-tradefed run commandAndExit cts-dev -m CtsPermission2TestCases
Test: bit FrameworksServicesTests:com.android.server.pm.PackageManagerSettingsTests
Change-Id: I616184fa2135a11687e4ce615884f861466fdebe