serve zipped. json manifests

[mrcjkb]

Hey 👋

To work around luarocks/luarocks#1797, luarocks 3.12 now parses the manifest from JSON.
luarocks.org also serves zipped manifests, (e.g. https://luarocks.org/manifest-5.1.zip), but these only contain the Lua manifest.
In terms of network bandwidth, downloading and unpacking the zipped manifest is preferable.
Would it be possible to include the JSON manifest in the zip download?
Perhaps via https://luarocks.org/manifest-<version>.json.zip, so that clients can choose which one they want?

cc @hishamhm (if luarocks also uses the zipped manifest, it may still run into the luajit limitation).

[hishamhm]

PRs are welcome!

[mrcjkb]

I had a look at it (haven't been able to get the environment set up for running the site yet though).

It looks like it's more complicated than I thought it would be.
The json manifest is served by returning a { json = <lua_manifest> } table.
To serve a zipped json manifest, one would have to first serialise it to json (perhaps with the dkjson library) and then zip it.
json and "zippable" lua manifests are handled very differently and implementing zippable json manifests would likely require a major refactor - which I currently don't have the resources for.

I'll have to come back to this another time 😟