refactor: migrate from TypeScript to JavaScript

[caugner]

Summary

Migrates from TypeScript to JavaScript.

Test results and supporting details

Consistency with other repositories, and improved performance (e.g. 10% on build).

Before

% time npm run build

> @mdn/browser-compat-data@7.2.2 build
> tsx scripts/build/index.ts

Wrote: build/LICENSE
Wrote: build/package.json (manifest)
Wrote: build/require.d.ts (CommonJS types)
Wrote: build/legacynode.mjs (wrapper for old NodeJS versions)
Wrote: build/README.md
Wrote: build/import.d.mts (ESM types)
Wrote: build/data.json (data)
Wrote: build/types.d.ts (data types)
Data bundle is ready
npm run build  5.33s user 0.35s system 122% cpu 4.622 total

After

% time npm run build

> @mdn/browser-compat-data@7.2.2 build
> node scripts/build/index.js

Wrote: build/LICENSE
Wrote: build/package.json (manifest)
Wrote: build/legacynode.mjs (wrapper for old NodeJS versions)
Wrote: build/require.d.ts (CommonJS types)
Wrote: build/README.md
Wrote: build/import.d.mts (ESM types)
Wrote: build/types.d.ts (data types)
Wrote: build/data.json (data)
Data bundle is ready
npm run build  4.89s user 0.31s system 121% cpu 4.290 total
```

#### Related issues

Similar to https://github.com/mdn/dex/pull/95/.

[github-actions]

This pull request has merge conflicts that must be resolved before it can be merged.

[github-actions]

Tip: Review these changes grouped by change (recommended for most PRs), or grouped by feature (for large PRs).

[github-actions]

This pull request has merge conflicts that must be resolved before it can be merged.