Better implementation of maps_freq: convert ts_types to TsType in EvalSetup and modify usage in code

[lewisblake]

Change Summary

The goal here is to have all ts_type-like objects defined in a config be converted to actual TsType instances so that they do not need to be converted all over the place later in the code. This PR therefore defines the interface of having all TsType attributes defined upon config initialization. Will need to make TsType JSON serializable, and think about its structure. Longer-term project at it breaks a lot of tests and current functionality. Probably something to talk about at a design workshop. I think this approach is preferable but maybe there are other ideas worth considering.

Related issue number

Related to #1259

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 80.76923% with 5 lines in your changes missing coverage. Please review.

Project coverage is 78.99%. Comparing base (1bf6fc2) to head (4a92c07).
Report is 50 commits behind head on main-dev.

Files	Patch %	Lines
pyaerocom/aeroval/setupclasses.py	82.60%	4 Missing ⚠️
pyaerocom/tstype.py	66.66%	1 Missing ⚠️

Additional details and impacted files

@@             Coverage Diff              @@
##           main-dev    #1267      +/-   ##
============================================
+ Coverage     78.96%   78.99%   +0.03%     
============================================
  Files           133      134       +1     
  Lines         20599    20728     +129     
============================================
+ Hits          16265    16375     +110     
- Misses         4334     4353      +19     

Flag	Coverage Δ
unittests	78.99% <80.76%> (+0.03%)	⬆️

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