unix/mpbtstackport_common: Implement mp_bluetooth_hci_active.
unix/mpbtstackport_common: Implement mp_bluetooth_hci_active.

So that BTSTACK can be enabled with SYNC_EVENTS.

Signed-off-by: Damien George <99e6b749acbfbe2a596df99e91d24d6e1fdbee00@micropython.org>

adafruit/circuitpython,henriknelson/micropython,bvernoux/micropython,bvernoux/micropython,adafruit/circuitpython,adafruit/circuitpython,henriknelson/micropython,adafruit/circuitpython,adafruit/circuitpython,bvernoux/micropython,henriknelson/micropython,bvernoux/micropython,adafruit/circuitpython,henriknelson/micropython,bvernoux/micropython,henriknelson/micropython