Enable TCP KEEPALIVE to RFLink for dead connection detection (#46438)

RFLink compoment when used over TCP protocol suffers a major issue : it doesn't
know when connection is timeout or lost because there is no keepalive mechanism
so it can stay disconnected forever.
I wrote a small patch for the underlying 'python-rflink' library which will enable
TCP KEEPPAlive. On HASSIO side it will just add an optional argument in yml file
which will propagate to python-rflink caller.