Migrated/refactored switchbot.bluetooth integration.

- Out `gattlib` + `pybluez`, in `bleak`. It's not platform-dependent, it doesn't
  require libboost and other heavy build dependencies, and it doesn't require the
  user that runs the service from having special privileges to access raw
  Bluetooth sockets.

- Better integration with Platypush native entities. The devices are now mapped
  to write-only `EnumSwitch` entities, and the status returns the serialized
  representation of those entities instead of the previous intermediate
  representation.

docs/source/conf.py

@@ -296,6 +296,7 @@ autodoc_mock_imports = [
     'aiofiles',
     'aiofiles.os',
     'async_lru',
+    'bleak',
 ]
 
 sys.path.insert(0, os.path.abspath('../..'))