AIDA: FieldBuffer::to_string: 0-prefix hexadecimals according to type
AIDA: ClientConnectionImpl::signal_disconnect: return disconnection success

* avoid permanent critical.
AIDA: server: properly return to disconnection success to remote
PYTESTS: assert disconnection success
Merge branch 'aida-signal-disconnect'

* aida-signal-disconnect:
  PYTESTS: assert disconnection success
  AIDA: server: properly return to disconnection success to remote
  AIDA: ClientConnectionImpl::signal_disconnect: return disconnection success
  AIDA: FieldBuffer::to_string: 0-prefix hexadecimals according to type