Help React Native import @apollo/client/main.cjs and other CommonJS bundles

[benjamn]

We use the .cjs file extension for our CommonJS bundle entry points (such as @apollo/client/core/core.cjs) to indicate to Node.js that "type": "module" in @apollo/client/package.json does not apply to those files.

Without additional configuration of its Metro bundler, React Native refuses to resolve .cjs files by default, but it will attempt to append various file extensions, including the (relatively) React Native-specific ending .native.js. By providing a dist/**/*.cjs.native.js file for every existing dist/**/*.cjs file we ship, React Native should always have a safe fallback to find the right code.

If this works, it will completely supersede/obviate the manual advice involving metro.config.js we added to CHANGELOG.md in #9084.

There is some risk of the dual package hazard (importing the same module multiple times unexpectedly), but as long as Metro consistently resolves the .native.js version of the file, all should be well. Apollo Client should completely ignore the .native.js version of the file, so React Native is the only reason those alternate modules should ever be used.

This PR incorporates the following PRs for dependency packages that also used .cjs bundle files:

• Generate index.cjs.native.js to help React Native resolve index.cjs zen-observable-ts#273
• Provide lib/invariant.cjs.native.js and process/main.cjs.native.js for React Native invariant-packages#293

Issues potentially fixed:

• The suggested .cjs resolver fix on 3.5.4 adds 10 seconds of boot on iOS. #9437

[benjamn]

The .cjs.native.js files are just copies of the corresponding .cjs files, to be clear.

I thought about making each .cjs.native.js file a thin CommonJS wrapper that re-exports the .cjs module's exports (like module.exports = require("./main.cjs")) but Metro doesn't like require("./main.cjs") for the same reasons as before, and even if it did accept that style of code, it would have to be careful not to resolve ./main.cjs back to the current ./main.cjs.native.js module after appending .native.js again.

I also thought about making the .cjs.native.js files be symbolic links to the .cjs files, but my experience suggests symlinks aren’t portable (Windows). Happy to explore other ideas here if there's interest.

[brainkim]

Thank you for investigating this, Ben! I don’t have the bandwidth right now to spin up a React Native project so I will rubber-stamp approve this, having only looked at the files.