Convert transfocator to ophyd_async

[shihab-dls]

Fixes #748

Instructions to reviewer on how to test:

1. Check if signal components converted to analogous ophyd_async types.
2. Check if setting device results in expected behaviour.

Checks for reviewer

• Would the PR title make sense to a scientist on a set of release notes
• If a new device has been added does it follow the standards
• If changing the API for a pre-existing device, ensure that any beamlines using this device have updated their Bluesky plans accordingly
• Have the connection tests for the relevant beamline(s) been run via dodal connect ${BEAMLINE}

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 97.42%. Comparing base (fa78284) to head (0cc4c6a).
Report is 1 commits behind head on main.

Additional details and impacted files

@@            Coverage Diff             @@
##             main     #941      +/-   ##
==========================================
+ Coverage   97.38%   97.42%   +0.03%     
==========================================
  Files         143      143              
  Lines        6087     6087              
==========================================
+ Hits         5928     5930       +2     
+ Misses        159      157       -2     

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[olliesilvester]

CI initially failed due to a flakey unit test unrelated to this PR, it passed after re-running. See #943

[olliesilvester]

Thanks, this looks great so far!

I've left a few comments, but the main one is something I incorrectly suggested to you, which was to not bother running set in the background by using asyncio.create_task. The original code ran set asynchronously, so we should try to keep that.

By the way, if you're curious, this was the recently added policy for reviews in dodal: https://diamondlightsource.github.io/dodal/main/explanations/reviews.html

[olliesilvester]

Looks mostly good now, just a couple more things. When you're happy with this, we can create a short bluesky plan to test this device on the beamline

[olliesilvester]

This seemed to work well during testing. A few minor features were requested by David on I04:

• Add the signals for the read-back values for the number of lenses and the vertical beam size, BL04I-MO-FSWT-01:NUM_FILTERS and BL04I-MO-FSWT-01:VER
• After the set is done, log the readbacks for the above

[olliesilvester]

Thanks! Looks neater than the old device 🥳

[DominicOram]

Must: I think there's a potential infinite loop here. See #995

[DominicOram]

Could: I always think nonlocal is a bit of a code smell. For example, in this case we could just return the value but I'm also not 100% sure of the purpose of is_set_filters_done