add pya init command

[jgriesfeller]

Change Summary

The title says it all

Related issue number

fix #1401

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 75.00000% with 4 lines in your changes missing coverage. Please review.

Project coverage is 78.58%. Comparing base (c8b2b28) to head (3bc258a).
Report is 18 commits behind head on main-dev.

Files with missing lines	Patch %	Lines
pyaerocom/scripts/cli.py	75.00%	4 Missing ⚠️

Additional details and impacted files

@@             Coverage Diff              @@
##           main-dev    #1402      +/-   ##
============================================
+ Coverage     78.56%   78.58%   +0.01%     
============================================
  Files           137      137              
  Lines         20905    20899       -6     
============================================
- Hits          16424    16423       -1     
+ Misses         4481     4476       -5     

Flag	Coverage Δ
unittests	78.58% <75.00%> (+0.01%)	⬆️

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[thorbjoernl]

Minor suggestions, otherwise LGTM