Fix exception handling in getState() binder cache

Bug: 153103051

A binder cache recompute() function cannot compute a result based on any
data that is not known to the binder server.  If the code depends on
local data that can change, then invalidation will not work properly.

The original getState() method returned OFF if the bluetooth service was
unavailable.  This computation now occurs in the getStateInternal()
method, outside of the binder cache query() method.

The recompute() method converts RemoteExceptions to RuntimeExceptions.
Then, the conversion is reversed in getStateInternal().  This double
conversion is needed because the cache recompute() method has no throw
spec.

Test: Create a debug image that enables binder cache VERIFY.  Run the
following tests:
 * atest BluetoothInstrumentationTests
 * atest PtsChreTestCases
 * atest UserLifecycleTests
 * manual testing connecting to bluetooth devices and toggling airplane
   mode.
No cache inconsistencies found.  No test failures seen.

Change-Id: I93b9742587c4eb695d9a11fc6ab145f6a40a0ece