feat: add separate permission to check for writable files

[susnux]

There is a difference if a file is only updateable (allow to update it means rename or move) or if the file is writable (content can be changed).
Needed to use erasable syntax as Typescript enums do not allow entries with the same value.

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 86.42%. Comparing base (9febf8f) to head (62d4dd8).
⚠️ Report is 10 commits behind head on main.

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #1455      +/-   ##
==========================================
- Coverage   86.72%   86.42%   -0.31%     
==========================================
  Files          27       27              
  Lines         723      707      -16     
  Branches      196      197       +1     
==========================================
- Hits          627      611      -16     
  Misses         82       82              
  Partials       14       14              

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