Merge changes I50fd0400,If772cc72,I6f6845d1,Ib6911767,I4c754fd6, ...

* changes:
  floss: Refactor callback registration
  floss: Client checks if manager is valid
  floss: Improve bonding procedure
  floss: ConnectAllEnabledProfiles now connects A2DP
  floss: Implement ConnectAllEnabledProfiles + Disconnect
  floss: Add bond remove and cancel to btclient
  floss: Implement GetConnectionState
  floss: Add support for BtConnectionCallbacks
  floss: Add floss enable/disable to btclient
  floss: Refactor DisconnectWatcher to take id