ssh client: patch over the differences with the zmq client

[oliver-sanders]

The SSH client does not inherit from the ZMQ client so their functionality has drifted a little e.g. the SSH client does not support the timeout_handler which can detect when workflows have stopped or restarted.

Suggest refactoring out a common base class with two concrete implementations.

Should be suitable for a later release candidate (no interface changes).

Pull requests welcome!

[MetRonnie]

Was thinking the same, happy to take this on in the near future

[MetRonnie]

Is this https://github.com/cylc/cylc-flow/blob/4ca97df6b05e3670dae42ca4d5e680912d0cfdbc/cylc/flow/network/client.py#L199-L201

specific to the ZMQ WorkflowRuntimeClient or should it be moved into the shared timeout_handler method?

[oliver-sanders]

That should be shared logic.

[dwsutherland]

Eventually this may be share with HTTP also (if we can ever get the CLI via hub/server working)