[ReadMscwCtm] Supporting selecting files to be read by regexp match

[thorbjoernl]

Change Summary

Support providing a custom regular expression to the EMEP reader which can be used to select files instead of the Base_{freq}.nc` matching that is currently being used.

Currently works with concatenated files.

Related issue number

• Evaluation of uemep output in pyaeroval #1175

Checklist

• Start with a draft-PR
• The PR title is a good summary of the changes
• PR is set to AeroTools and a tentative milestone
• Documentation reflects the changes where applicable
• Tests for the changes exist where applicable
• Tests pass locally
• Tests pass on CI
• At least 1 reviewer is selected
• Make PR ready to review

[codecov]

Codecov Report

Attention: Patch coverage is 92.30769% with 3 lines in your changes missing coverage. Please review.

Project coverage is 78.57%. Comparing base (413f9b8) to head (db847b5).
Report is 16 commits behind head on main-dev.

Files with missing lines	Patch %	Lines
pyaerocom/io/mscw_ctm/reader.py	92.30%	3 Missing ⚠️

Additional details and impacted files

@@             Coverage Diff              @@
##           main-dev    #1423      +/-   ##
============================================
+ Coverage     78.35%   78.57%   +0.22%     
============================================
  Files           137      137              
  Lines         20889    20893       +4     
============================================
+ Hits          16367    16417      +50     
+ Misses         4522     4476      -46     

Flag	Coverage Δ
unittests	78.57% <92.30%> (+0.22%)	⬆️

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[thorbjoernl]

Closing because changes are merged with #1425