chore: use node 22 Set methods for websocket close state

[trivikr]

This relates to...

N/A

Rationale

Node.js 22 supports the new Set relation methods, which make the WebSocket closing-handshake checks more explicit. This change centralizes the closing-handshake state set in the WebSocket constants module and reuses it across the WebSocket implementation instead of redefining it in multiple files.

Changes

• Add closingHandshakeStates to the WebSocket constants module
• Document closingHandshakeStates with JSDoc
• Replace duplicated local closing-handshake sets with the shared constant
• Use Set.prototype.isDisjointFrom() and Set.prototype.isSupersetOf() for closing-handshake checks

Features

N/A

Bug Fixes

N/A

Breaking Changes and Deprecations

N/A

Status

• I have read and agreed to the Developer's Certificate of Origin
• Tested
• Benchmarked (optional)
• Documented
• Review ready
• In review
• Merge ready

[codecov-commenter]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 92.96%. Comparing base (48c7cf3) to head (0489090).
⚠️ Report is 4 commits behind head on main.

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #4974      +/-   ##
==========================================
- Coverage   92.96%   92.96%   -0.01%     
==========================================
  Files         111      111              
  Lines       35864    35852      -12     
==========================================
- Hits        33342    33330      -12     
  Misses       2522     2522              

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[mcollina]

lgtm