AreaDetector for electron analysers

[oliwenmandiamond]

Fixes #2084.

Instructions to reviewer on how to test:

1. Check implementation makes sense.
2. Check tests pass

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 99.14%. Comparing base (7916b43) to head (7ad5c10).

Additional details and impacted files

@@           Coverage Diff           @@
##             main    #2088   +/-   ##
=======================================
  Coverage   99.14%   99.14%           
=======================================
  Files         344      344           
  Lines       13388    13403   +15     
=======================================
+ Hits        13274    13289   +15     
  Misses        114      114           

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