Refactor permissions code for bluetooth controller enabler

Bluetooth may be disabled for a user. This CL refactors the code
that determines this a bit so we can query that without having to
have the UI open.

Test: robotests still pass
Bug: 62022517
Change-Id: Ic0837d21bdc4007a20d6ad138753d4f5d37ceceb
Merged-In: I3b54529865e16b7e1640b0adda7f7edb9d1a41f7