Returning capitalized aperture value name for ApertureValue enum

[shihab-dls]

Fixes #452

Instructions to reviewer on how to test:

1. Check if ApertureValue, formatted as a comment, returns names such as "Small" instead of "ApertureValue.SMALL".

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 97.17%. Comparing base (f9b3fd0) to head (4b25999).
Report is 1 commits behind head on main.

Additional details and impacted files

@@           Coverage Diff           @@
##             main     #953   +/-   ##
=======================================
  Coverage   97.17%   97.17%           
=======================================
  Files         134      134           
  Lines        5629     5631    +2     
=======================================
+ Hits         5470     5472    +2     
  Misses        159      159           

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[olliesilvester]

Thanks, looks good!