feat: Run blocking plans via websockets

[tpoliaw]

As an intermediate step before (or instead of?) redesigning the server sub-process handling, add a websocket endpoint to run the same submit-listen-start approach that the client runs remotely. This is an experimental feature subject to change in minor releases in future. Everything is opt-in and existing behaviour should not change.

For the CLI, the websocket connection is enabled using the --ws flag to the run subcommand. A stomp configuration will not be required in this case.

For the BlueapiClient, users should use the run_blocking method instead of the run_task. The signatures and behaviour are the same (other than the ignored timeout parameter of run_task).

On the server there is a new endpoint on the new /api/v2/ tree. This re-uses the existing submit and start methods on the task runner but adds a new subscribe method to pipe events from the worker process to the websocket.

[tpoliaw]

Rough next steps in no particular order

• Move websocket client method into BlueapiRestClient
• Add wrapper method in BlueapiClient?
• Add unstable/preview --ws flag to cli run method
• Deal with auth. Browser websocket api can't set headers
• Users + user-agents
• Include data/progress events
• Add service/meta events for error handling etc
• Handle client aborting
• Check interaction with server being busy
• Wrap pipe/unpipe into something that doesn't need finally handling
• See what happens when listeners fall over/slow down - do messages back up
• Add middleware for debug logging

[abbiemery]

• store api url withouth scheme, and add scheme to http and ws calls respectively. (request_and_deserialise)

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 96.31%. Comparing base (5d7e2fa) to head (f304709).

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #1413      +/-   ##
==========================================
+ Coverage   95.96%   96.31%   +0.35%     
==========================================
  Files          45       46       +1     
  Lines        3323     3641     +318     
==========================================
+ Hits         3189     3507     +318     
  Misses        134      134              

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[tpoliaw]

Should probably have a way for plans run via the plan cache to use websockets. They currently default to using the existing message bus approach. Something like

bc = BlueapiClient.from_config_file(...)
bc.use_ws(True)

bc.plans.count(detectors=[bc.devices.det])

It's not ideal though so open to suggestions. A new client only config field?

[fajinyuan]

please see my comments.

[fajinyuan]

one more use case - stop or abort after current point, ensure data collected so far are saved. like finish earlier!

[abbiemery]

Approved. It works locally for me as expected, but given the size of the PR I think we just get it into a release and let people play with it.