fix: more robust remote files generation

[dummdidumm]

We tried very hard to get manualChunks to work (see #14632 for the latest attempt) but it just doesn't quite work out. What we need is to actually have Vite/Rollup know about the proper entry points to then resolve everything from there. The problem previously was that we didn't know of a good way to know which entry points we have on the fly.

Turns out, this.emitFile is our savior (https://rollupjs.org/plugin-development/#this-emitfile). We can use it to create entry points while traversing the module graph and have Vite/Rollup wire up everything correctly.

Fixes #14679
Fixes #14708
Fixes #14736

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[alexbjorlig]

If it’s possible to prioritize this PR, I’d greatly appreciate it 🙏
We’re currently blocked on version 2.38.1, and updating to the latest version would help us move forward — including with our Rolldown testing.

[teemingc]

Commenting just so it's easy to find the historical context of this again: #14293 is the PR that introduced the manualChunks solution for finding remote functions in node_modules.

[dummdidumm]

Tried to come up with a good testcase, alas there's nothing sensible except the repositories themselves, and even they may change depending on module ordering etc.
So I think we have to go without a test on this one.