Publish current run from v4/container/state endpoint

[rossgray]

Pull request outline

As well as publishing the current run, there are a few more changes in here (looking at the commits individually will help review):

• refactor the execution_handler slightly
  • move into a run services module
  • it now returns the result and status code rather than just the result
• update a few dependencies (including httpx)
• update the tests
  • needed to use an async client in order to mock certain behaviour (if we don't use an async client we get issues mocking things as they run in a different event loop to the API)

Checklist:

• Tests written
• Version bumped

[linear]

PC-1176 Publish current run from resource monitor

[plutopulp]

LGTM, although maybe another pair of eyes may be good as not super familiar with the code.