Code mirror work

[videlais]

Extensive work to add syntax highlighting and Code Mirror tools.

This addresses issue #20 and PR #475. These are YEARS OLD issues that should now be resolved with the additional of new editor extensions added to Twine.

[codecov]

Codecov Report

❌ Patch coverage is 84.64164% with 45 lines in your changes missing coverage. Please review.
✅ Project coverage is 92.45%. Comparing base (3c4a10a) to head (8a92aa1).
⚠️ Report is 16 commits behind head on main.

Files with missing lines	Patch %	Lines
src/DOMUtils.js	75.75%	18 Missing and 6 partials ⚠️
src/ServiceContainer.js	56.75%	15 Missing and 1 partial ⚠️
src/ServiceRegistry.js	78.26%	5 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #1107      +/-   ##
==========================================
- Coverage   98.38%   92.45%   -5.94%     
==========================================
  Files          12       15       +3     
  Lines         496      636     +140     
  Branches       94      160      +66     
==========================================
+ Hits          488      588     +100     
- Misses          8       41      +33     
- Partials        0        7       +7     

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