feat: implement language plugin

[yeonjuan]

fixes #288

[codecov]

Codecov Report

Attention: Patch coverage is 83.63636% with 18 lines in your changes missing coverage. Please review.

Project coverage is 97.96%. Comparing base (2028683) to head (6eaef58).
Report is 1 commits behind head on main.

Files with missing lines	Patch %	Lines
...es/eslint-plugin/lib/languages/html-source-code.js	72.72%	15 Missing and 3 partials ⚠️

❌ Your patch check has failed because the patch coverage (83.63%) is below the target coverage (90.00%). You can increase the patch coverage or adjust the target coverage.

Additional details and impacted files

@@            Coverage Diff             @@
##             main     #323      +/-   ##
==========================================
- Coverage   98.72%   97.96%   -0.77%     
==========================================
  Files          73       76       +3     
  Lines        2199     2309     +110     
  Branches      604      633      +29     
==========================================
+ Hits         2171     2262      +91     
- Misses         28       44      +16     
- Partials        0        3       +3     

Flag	Coverage Δ
unittest	97.96% <83.63%> (-0.77%)	⬇️

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Files with missing lines	Coverage Δ
packages/eslint-plugin/lib/index.js	100.00% <100.00%> (ø)
...kages/eslint-plugin/lib/languages/html-language.js	100.00% <100.00%> (ø)
...eslint-plugin/lib/languages/html-traversal-step.js	100.00% <100.00%> (ø)
packages/eslint-plugin/tests/rule-tester.js	95.23% <100.00%> (-4.77%)	⬇️
...es/eslint-plugin/lib/languages/html-source-code.js	72.72% <72.72%> (ø)

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