fs: support removing read-only files in rmSync on Windows

[SparshGarg999]

Summary

Ensure fs.rmSync can delete read-only files and directories containing them on Windows when Node is built with clang libc++ (e.g. inside Electron).

Description

Since the migration to std::filesystem::remove and std::filesystem::remove_all on Windows, Node's fs.rmSync behaves differently depending on whether it was built with MSVC STL or clang libc++.

MSVC STL's implementation of std::filesystem::remove automatically clears the read-only attribute of a file before attempting to delete it. However, libc++'s implementation on Windows does not clear the read-only attribute, which causes the deletion to fail with operation_not_permitted (EPERM). This issue directly impacts downstream platforms like Electron that compile Node.js with libc++ on Windows (see electron/electron#52253).

This commit introduces a Windows-specific helper ClearReadOnlyAttributeW in src/node_file.cc that is called if operation_not_permitted is encountered. It manually clears the FILE_ATTRIBUTE_READONLY attribute from the file (or recursively from files inside a directory) and retries the removal operation, bringing libc++ builds to parity with MSVC STL builds.

Verification

Added a new test in test/parallel/test-fs-rm.js that makes files read-only using fs.chmodSync(file, 0o444) (which sets the file attribute on Windows) and validates that fs.rmSync can delete them both directly and recursively as part of a directory.

Fixes: #64374

[codecov]

Codecov Report

❌ Patch coverage is 0% with 1 line in your changes missing coverage. Please review.
✅ Project coverage is 90.24%. Comparing base (892976d) to head (8d6ce84).
⚠️ Report is 13 commits behind head on main.

Files with missing lines	Patch %	Lines
src/node_file.cc	0.00%	0 Missing and 1 partial ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main   #64453      +/-   ##
==========================================
- Coverage   90.24%   90.24%   -0.01%     
==========================================
  Files         741      741              
  Lines      241424   241603     +179     
  Branches    45494    45523      +29     
==========================================
+ Hits       217883   218025     +142     
- Misses      15085    15112      +27     
- Partials     8456     8466      +10     

Files with missing lines	Coverage Δ
src/node_file.cc	74.19% <0.00%> (ø)

... and 31 files with indirect coverage changes

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