test_runner: preserve user flags in argv

[Han5991]

Fixes: #61852

This PR fixes an issue where user-specified flags were being stripped from process.argv when running with the --test flag.

Previously, the test runner treated all arguments as potential file patterns, ignoring flags that weren't specific to the test runner. This made it impossible to pass custom flags (e.g., --hello) to test files.

This change ensures that:

1. Arguments following -- are correctly treated as user arguments.
2. Arguments starting with - (that are not consumed by Node.js or the test runner) are preserved and passed to the test process.

Added new tests in test/parallel/test-runner-cli-args.js to verify:

• Implicit flag passing: node --test fixture.js --hello
• Explicit flag passing: node --test fixture.js -- --hello
• Mixed usage: node --test fixture.js --hello -- world

[nodejs-github-bot]

Review requested:

• @nodejs/test_runner

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 89.73%. Comparing base (4f13746) to head (24a021f).
⚠️ Report is 3 commits behind head on main.

Additional details and impacted files

@@            Coverage Diff             @@
##             main   #61858      +/-   ##
==========================================
+ Coverage   89.72%   89.73%   +0.01%     
==========================================
  Files         675      675              
  Lines      204806   204826      +20     
  Branches    39355    39358       +3     
==========================================
+ Hits       183761   183803      +42     
+ Misses      13330    13295      -35     
- Partials     7715     7728      +13     

Files with missing lines	Coverage Δ
lib/internal/main/test_runner.js	100.00% <100.00%> (ø)

... and 35 files with indirect coverage changes

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