Improve I19 Filter Wheel 1 Selection

[CoePaul]

Addresses #2136

• Replaces brittle enumeration of I19 filter wheel one which was tightly coupled to interchangeable installed filters in favour of mapping to wheel slot locations. e.g. W1S4

• The mapping from slot label to absorber specifics and business logic exclusions etc has to be done outside this enum no matter what form it takes

• This change renders the labelling less brittle as old label AIR5 would have become redundant when slot 5 sees a future foil filter added.

• Note the abuse of an enum is (temporarily at least) a necessary evil imposed by the assumptions in the design of the standard FilterWheel class

Instructions to reviewer on how to test:

1. See if You agree with the explanation of rationale behind the change
2. Confirm no CI tests ( nor dodal connect ) is affected ( the latter shouldn't be as the filter wheel device is skipped for now )

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 99.16%. Comparing base (4463efb) to head (8613d22).

Additional details and impacted files

@@           Coverage Diff           @@
##             main    #2137   +/-   ##
=======================================
  Coverage   99.16%   99.16%           
=======================================
  Files         354      354           
  Lines       13832    13832           
=======================================
  Hits        13716    13716           
  Misses        116      116           

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