Initial schema validator frontend support

[nellh]

This fixes some of the remaining issues with using the schema validator client side.

• Allows site admins to configure which validator to use, defaulting the existing JS validator for regular users.
• Displays the Issue content better so it's more useful for debugging.
• Runs as its own worker.

This does not include the server side components, which is setting the option on the dataset to toggle which is used for display and running both validators on each change.

Also the entire schema validator is included here for testing this but ideally it would be an import from a CI build on the bids-validator repo. This is just the latest output of build.ts with one line added to have TypeScript ignore it as an external dependency.

[codecov]

Codecov Report

Merging #2779 (1c0c165) into master (b42b1a7) will increase coverage by 0.26%.
The diff coverage is 58.62%.

❗ Current head 1c0c165 differs from pull request most recent head a16187e. Consider uploading reports for the commit a16187e to get more accurate results

@@            Coverage Diff             @@
##           master    #2779      +/-   ##
==========================================
+ Coverage   75.78%   76.05%   +0.26%     
==========================================
  Files         409      412       +3     
  Lines       67092    67133      +41     
  Branches     2035     2048      +13     
==========================================
+ Hits        50843    51055     +212     
+ Misses      16199    16027     -172     
- Partials       50       51       +1     

Impacted Files	Coverage Δ
...c/scripts/validation/validation-results.issues.jsx	73.19% <55.55%> (-8.29%)	⬇️
...pts/validation/validation-results.issues.issue.jsx	85.55% <100.00%> (ø)
...-app/src/scripts/validation/validation-results.jsx	74.00% <100.00%> (ø)

... and 29 files with indirect coverage changes

📣 We’re building smart automated test selection to slash your CI/CD build times. Learn more