feat: new --edit option to edit config file in editor

[frostming]

Signed-off-by: Frost Ming me@frostming.com

Pull Request Checklist

• A news fragment is added in news/ describing what is new.
• Test cases added for changed code.

Describe what you have changed in this PR.

[codecov-commenter]

Codecov Report

Patch coverage: 26.66% and project coverage change: -0.19 ⚠️

Comparison is base (cd4c06d) 85.18% compared to head (1710f7c) 84.99%.

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Additional details and impacted files

@@            Coverage Diff             @@
##             main    #2028      +/-   ##
==========================================
- Coverage   85.18%   84.99%   -0.19%     
==========================================
  Files          99       99              
  Lines        9382     9411      +29     
  Branches     2048     2058      +10     
==========================================
+ Hits         7992     7999       +7     
- Misses        943      964      +21     
- Partials      447      448       +1     

Flag	Coverage Δ
unittests	84.79% <26.66%> (-0.19%)	⬇️

Flags with carried forward coverage won't be shown. Click here to find out more.

Impacted Files	Coverage Δ
src/pdm/cli/commands/config.py	72.16% <26.66%> (-20.49%)	⬇️

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