Split up napi envs

[heimskr]

What does this PR do?

This PR allows multiple napi envs per global object to exist at once.

• Documentation or TypeScript types (it's okay to leave the rest blank in this case)
• Code changes

How did you verify your code works?

Ran our napi tests and made sure none of Node's napi tests failed compared to the current stable release of Bun.

[robobun]

^{Updated 4:44 PM PT - Jan 8th, 2025}

✅ @190n, your commit f73edb4 has passed in #9261! 🎉

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🧪   try this PR locally:

bunx bun-pr 15437

[heimskr]

Whoops, tried to use dlsym on Windows

[190n]

Review comments + this needs a test