Fallback to javascript highlighting in the source view as a backup

[canova]

This might be a bit controversial as we are now falling abck to javascript highlighting for all the unkown sources. But I feel like it's an okay compomise. The main issue is that inline scripts share the page URL as the file name, and this doesn't include the .js extension, so it's impossible to know if they are indeed JS from the file path. Falling back to javascript for all unkown can have false positives for unkown file types, but I think that's fine.

STR:

• Enable "JavaScript Sources" feature in about:profiling
• Start the profiler.
• Navigate to https://canova.dev/testcase/inline-scripts.html
• Wait until the page loads (~4 seconds jank).
• Once it loads, capture a profile.

[codecov]

Codecov Report

❌ Patch coverage is 0% with 1 line in your changes missing coverage. Please review.
✅ Project coverage is 85.45%. Comparing base (c886717) to head (f114574).
⚠️ Report is 1 commits behind head on main.

Files with missing lines	Patch %	Lines
src/components/shared/SourceView-codemirror.ts	0.00%	1 Missing ⚠️

Additional details and impacted files

@@           Coverage Diff           @@
##             main    #5936   +/-   ##
=======================================
  Coverage   85.45%   85.45%           
=======================================
  Files         321      321           
  Lines       32139    32139           
  Branches     8850     8764   -86     
=======================================
  Hits        27463    27463           
  Misses       4241     4241           
  Partials      435      435           

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[mstange]

Seems fine to me.