WebSerial support via Pyodide

[puddly]

Fixes #58.

This PR implements a webserial transport via pyodide. You explicitly register serial ports with serialx.platforms.serial_pyodide.register_js_port from the JS side and then connect to the named port from the Python side. Surprisingly, the test suite (including coverage!) runs with minimal modifications from within pyodide. I've added this to CI via Bun.

[codecov]

Codecov Report

❌ Patch coverage is 94.14634% with 12 lines in your changes missing coverage. Please review.
✅ Project coverage is 90.77%. Comparing base (765e856) to head (965e1f6).
⚠️ Report is 1 commits behind head on dev.

Files with missing lines	Patch %	Lines
serialx/platforms/serial_pyodide/__init__.py	93.02%	12 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##              dev      #70      +/-   ##
==========================================
+ Coverage   90.48%   90.77%   +0.28%     
==========================================
  Files          19       21       +2     
  Lines        3143     3348     +205     
==========================================
+ Hits         2844     3039     +195     
- Misses        299      309      +10     

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[puddly]

Tracing doesn't seem to work properly with pyodide unfortunately so the generated coverage isn't complete. I've excluded it until that's fixed upstream.

Never mind, I've got a workaround.