service: Add IBluetooth interface definition

This CL adds the initial IBluetooth interface definition. Client and server
proxy classes have been added, which would normally be autogenerated in Android
Framework Land. This currently only includes the first five methods from
IBluetooth.aidl but will be extended in the future.

Bug: 22743677
Change-Id: I32be9801e91877c2961e24232cdfaecd80ee2368