diagnostics_channel: add diagnostics channels for web locks

[IlyasShabi]

This PR adds diagnostics channels support for locks.request() giving visibility into the lock request lifecycle.

Four channels are emitted:

• locks.request.start when a request begins
• locks.request.grant when the lock is granted
• locks.request.miss when the lock is not immediately available
• locks.request.end when the request finishes

[codecov]

Codecov Report

❌ Patch coverage is 89.47368% with 6 lines in your changes missing coverage. Please review.
✅ Project coverage is 89.63%. Comparing base (da5efc4) to head (8ce0c9b).
⚠️ Report is 92 commits behind head on main.

Files with missing lines	Patch %	Lines
lib/internal/locks.js	89.47%	6 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main   #62123      +/-   ##
==========================================
+ Coverage   88.84%   89.63%   +0.79%     
==========================================
  Files         674      676       +2     
  Lines      204957   206396    +1439     
  Branches    39309    39532     +223     
==========================================
+ Hits       182087   184997    +2910     
+ Misses      15088    13524    -1564     
- Partials     7782     7875      +93     

Files with missing lines	Coverage Δ
lib/internal/locks.js	94.39% <89.47%> (-0.70%)	⬇️

... and 225 files with indirect coverage changes

🚀 New features to boost your workflow:

• ❄️ Test Analytics: Detect flaky tests, report on failures, and find test suite problems.
• 📦 JS Bundle Analysis: Save yourself from yourself by tracking and limiting bundle sizes in JS merges.

[legendecas]

This channel callback has no parameter of Lock. What is this callback referring to?

[IlyasShabi]

Im referring to the user land callback passed to locks.request() not to the subscriber itself.