src: fix symlink issue, subtitution middleware hack

[flakey5]

Main changes:

• Adds build-r2-symlinks.mjs script
  • Replaces update-redirect-links.json, still creates latestVersion.json
  • src/constants/docsDirectory.json - cache of folders that exist in nodejs/docs/ so we can access them in the worker w/o the latency of another R2 call
  • src/constants/cachedDirectories.json - cache of the directory listings for nodejs/release/ and nodejs/docs/ with the symlinks added
• Fixed the temp hack that we had for the substitution middleware

Misc changes:

• Removed promote-release.mjs (unused)
• Renamed compile-handlebars.js to be an .mjs file
• Fixed typo w/ Request.unsubstitutedUrl

Fixes #163

[ovflowd]

I assume this is the built file?

[ovflowd]

Any reason why this cannot be inside the cachedDirectories folder? To reuse same logic and reduce the need of maintaining two different files and have centralised logic?

[flakey5]

We could, but it would mean that we'd need to store symlinks separately from the real files (something like

interface CachedDirectory {
  subdirectories: string[],
  symlinkSubdirectories: string[],
  files: File[],
  symlinkFiles: File[]
}

).

[ovflowd]

Very interesting. I wonder if this will be cached between workers so that it doesn't need to be read on every network request? I also wonder if somehow this gets cached or whatnot 🤔

Because I assume this file will keep increasing over time. We might want to consider using Git LFS to also prevent these files to be shown on diff.

[flakey5]

I wonder if this will be cached between workers

As in the contents of cachedDirectories.json? It's inlined along with the rest of the source files for the worker, so it's stored in-memory for each instance of the worker.

[ovflowd]

Instead of this, can you do this?:

const result = JSON.parse(input, function(key, value) {
    if (key == 'date') return new Date(Date.parse(value));
    return value;
});

Or something of sort? This speeds up the process and reduces the need of iterating everything again

[flakey5]

Since CACHED_DIRECTORIES is already an object I don't think so?

[ovflowd]

This is a first-pass comment, but it looks good so far. I left a few comments, and I plan to make another in-depth review later!

[ovflowd]

2nd pass. We're good to merge this PR!