rojo upload does not work with plugins

[Dekkonot]

An undetermined amount of time ago, rojo upload stopped working for plugins.

This is a bummer and we should see if it's possible. There's no endpoint that uses opencloud, but one does exist for cookies because Studio couldn't do it otherwise.

A look with a proxy says it's the same URL that Roblox Studio uses to upload places, so we could in theory support uploading places without open cloud again. I'm not sure if we want to though.

For reference, the URL is a PATCH to https://apis.roblox.com/assets/user-auth/v1/assets/{ASSET_ID} and it utilizes multipart form-data for uploading. I'll spare the details here but it's a bit more involved than it used to be.