PEP660 frontend for editable build

[frostming]

Pull Request Check List

• 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

Merging #612 (fb96049) into main (12c5c4f) will decrease coverage by 0.32%.
The diff coverage is 86.11%.

@@            Coverage Diff             @@
##             main     #612      +/-   ##
==========================================
- Coverage   84.40%   84.08%   -0.33%     
==========================================
  Files          72       72              
  Lines        6042     6039       -3     
  Branches     1075     1073       -2     
==========================================
- Hits         5100     5078      -22     
- Misses        649      663      +14     
- Partials      293      298       +5     

Flag	Coverage Δ
unittests	83.88% <86.11%> (-0.33%)	⬇️

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

Impacted Files	Coverage Δ
pdm/builders/base.py	91.21% <66.66%> (-0.57%)	⬇️
pdm/builders/editable.py	84.21% <84.00%> (-2.46%)	⬇️
pdm/installers/installers.py	97.27% <85.00%> (-0.39%)	⬇️
pdm/builders/sdist.py	100.00% <100.00%> (ø)
pdm/builders/wheel.py	100.00% <100.00%> (ø)
pdm/installers/manager.py	81.81% <100.00%> (-3.90%)	⬇️
pdm/installers/synchronizers.py	85.00% <100.00%> (+0.42%)	⬆️
pdm/models/candidates.py	89.36% <100.00%> (+1.75%)	⬆️
pdm/installers/uninstallers.py	75.87% <0.00%> (-7.54%)	⬇️
... and 4 more

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