Add @metamask/build-utils package

[rekmarks]

Explanation

In MetaMask/metamask-mobile#7734, code fence support was added to MetaMask Mobile by essentially copypasting the implementation from the extension. This PR extracts the shared logic from the extension and mobile implementations of code fencing into a new package, @metamask/build-utils, which can be imported into the respective clients. A draft integration in the extension can be found in MetaMask/metamask-extension#22033, which uses local copies of the built version of the new package.

@metamask/build-utils currently implements the shared logic for code fence parsing and removal,, as well as linting transformed files. The consumer is responsible for integrating the fence parser into the given build system, and configuring the ESLint instance used for linting.

Noteworthy changes / decisions made:

• ONLY_INCLUDE_IN has been renamed to ONLY_INCLUDE_IF, which is more in line with its actual usage.
  • When code fencing was originally implemented, we imagined that it would be used to differentiate between specific builds, e.g. "main" and "beta". Since then, the parameters of the command are labels corresponding to different features. Thus, fenced code is not included in certain builds so much as if certain features are enabled.
• The decision to only extract the removeFencedCode and lintTransformedFile functions was made for two reasons primarily:
  • The integrations of code fence removal in the extension / Browserify and mobile / Metro are significantly different.
  • The different applications have different ESLint configurations. It seems inappropriate to make this package responsible for being aware of the ESLint configs of the consumers.
    • See also: https://github.com/MetaMask/metamask-mobile/pull/7837/files#r1401408233

References

• Related to feat: enable code fence capabilities on mobile app.  metamask-mobile#7734
• Related to Replace local code fence transform with @metamask/build-utils metamask-extension#22033

Changelog

@metamask/build-utils

• Added: Initial release

Checklist

• I've updated the test suite for new or updated code as appropriate
• I've updated documentation (JSDoc, Markdown, etc.) for new or updated code as appropriate
• I've highlighted breaking changes using the "BREAKING" category above as appropriate

[socket-security]

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Packages	Version	New capabilities	Transitives	Size	Publisher
@types/eslint	8.44.7	None	+2	230 kB	types

[Jonathansoufer]

Good job! LGTM!

[mcmire]

I see that this is in devDependencies, but lintTransformedFile takes an argument that's of type ESLint. So, two questions:

1. Where does this type come from — does it come from this package or @types/eslint? Do we need both or just one?
2. ESLint will show up in the type definition file for src/transforms/utils.ts, so anyone who uses this library in a TypeScript will need that type in order to compile their code. We've encountered problems with this type of thing before and the solution has been to move the library in question to dependencies (e.g., Move eth-query back from devDeps to deps #3578). What are your thoughts on moving either eslint or @types/eslint to dependencies?