feat: experimental websocket support

[pi0]

🔗 Linked issue

❓ Type of change

• 📖 Documentation (updates to the documentation, readme, or JSdoc annotations)
• 🐞 Bug fix (a non-breaking change that fixes an issue)
• 👌 Enhancement (improving an existing functionality like performance)
• ✨ New feature (a non-breaking change that adds functionality)
• 🧹 Chore (updates to the build process or auxiliary tools and libraries)
• ⚠️ Breaking change (fix or feature that would cause existing functionality to change)

📚 Description

This PR adds experimental WebSocket support.

The new ws option can be enabled via options or CLI. When set via options and is a function, will be used as normal Node.js upgrade handler.

When is an object, listhen will use crossws API to listen on the hooks.

When is true (set by CLI), listhen dev server will support WebSocket with HMR (using a hooks proxy)

📝 Checklist

• I have linked an issue or discussion.
• I have updated the documentation accordingly.

[codecov]

Codecov Report

Attention: 118 lines in your changes are missing coverage. Please review.

Comparison is base (ebef2d1) 52.19% compared to head (7766a3f) 49.42%.

Files	Patch %	Lines
playground/index.ts	0.00%	54 Missing ⚠️
src/server/dev.ts	4.34%	44 Missing ⚠️
src/listen.ts	23.52%	13 Missing ⚠️
src/cli.ts	0.00%	5 Missing ⚠️
src/server/watcher.ts	0.00%	2 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main     #158      +/-   ##
==========================================
- Coverage   52.19%   49.42%   -2.78%     
==========================================
  Files          17       17              
  Lines        1686     1819     +133     
  Branches      145      147       +2     
==========================================
+ Hits          880      899      +19     
- Misses        801      915     +114     
  Partials        5        5              

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