Ensure we validate against correct SPOClassUID in pixl_dcmd tests

[p-j-smith]

Description

Fixes #580

• add MODALITY_TO_CLASS_UID dictionary to pytest_pixl.dicom module to map DICOM modality to SOPClassUID
• update test_anonymise_and_validate_dicom to ensure we validate against all modalities listed in all project configs
• add missing tags to base config files (some were missing but not picked up as we weren't validating against the correct modalities / SOPClassUID)
• move duplicated tags into base.yaml (otherwise test_merge_base_only_tags complains that tags are duplicated across config files)
• remove unused fixtures in pixl_dcmd tests (some tests were including fixtures that were not actually used / needed for the tests)
• rename vanilla_single_dicom_image_DX to vanilla_dicom_image_DX as the previous vanilla_dicom_image_DX fixture has been removed as not needed

Type of change

Please delete options accordingly to the description.

• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to not work as expected)
• This change requires a documentation update

Suggested Checklist

• I have performed a self-review of my own code.
• I have made corresponding changes to the documentation.
• My changes generate no new warnings.
• I have commented my code, particularly in hard-to-understand areas.
• I have passed on my local host device. (see further details at the CONTRIBUTING document)
• Make sure your branch is up-to-date with main branch. See CONTRIBUTING for a general example to syncronise your branch with the main branch.
• I have requested review to this PR.
• I have addressed and marked as resolved all the review comments in my PR.
• Finally, I have selected squash and merge

[codecov]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 87.29%. Comparing base (6435ebb) to head (07d4baf).
Report is 1 commits behind head on main.

Additional details and impacted files

@@            Coverage Diff             @@
##             main     #581      +/-   ##
==========================================
- Coverage   87.38%   87.29%   -0.10%     
==========================================
  Files          76       76              
  Lines        3386     3362      -24     
==========================================
- Hits         2959     2935      -24     
  Misses        427      427              

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[stefpiatek]

Thanks for spotting and fixing Paul!