bluetooth: Merge all ports into "bluetooth-input" and "bluetooth-output"
The card profile availability flag already provides all the necessary
information and therefore all Bluetooth ports can be merged, leaving
the two generic ones only: "bluetooth-input" and "bluetooth-output". The
availability of these port now represents whether the device is
streaming audio, with the following mapping:
- PA_AVAILABLE_UNKNOWN: some profile connected but not streaming
- PA_AVAILABLE_NO: no profiles connected
- PA_AVAILABLE_YES: some profile streaming (regardless of which)
Each port's flag represents the profiles with the corresponding I/O
capabilities (pa_direction_t).