Have app global connection as to other managers

Regular ...Manager-s connect to the system server hence there is no
problem establishing a permanent connection via
ServiceManager.getServiceOrThrow.

(1)
PermissionControllerManager connects to an app, hence the binding has to
be dynamic. This is done my using the local RemoteService class.

(2)
...Manager-s are per context. Hence when the context goes away all
service connection started for this service are supposed to also be
cleaned up. There is no callback when the context goes away.

(1) and (2) lead to RemoteService connection to still be bound while the
context goes away which causes a service connection leak.

This change emulates the behavior of regular managers by creating a
permanent RemoteService tied to the application context. Of course
interanlly RemoteService itself binds and unbinds dynamically. Still,
now the RemoteService is not bound to a context that goes away and no
connection is leaked.

Test: atest CtsAppSecurityHostTestCases:android.appsecurity.cts.PermissionsHostTest
      (this test failed before as settings was crashing due to leaked
      remote service connections)
Change-Id: I5b8a4c62070fcce6e390897d046c4b28998e3952