Bundle assets with spoke file for local backups and cross-instance exports

[camelgod]

I realize this is requires a pretty big change in the way that scenes are exported, but it would be very useful to allow spoke scene exports to include "everything" (assets) for transferring and backing up scenes.

We use multiple different instances (testing, dev, staging, production) and transferring spoke projects between these instances would be super useful without the objects simply containing links to the different assets. For example if the dev server is taken offline or changed down the line, the scene will not be importable in other environments.

It would also make it easier to collaborate across different environments (between different hubs cloud users + mozilla hubs users etc). It is very unpredictable right now to use other spoke scenes if their origin instance is taken offline or if you do not have all the CORS settings in check.

Right now there is AFAIK no way to back up spoke scenes, other than exporting the .spoke with all assets linked. The reason we want to back spoke scenes up in the first place is if the instance messes up and we need to reset it or otherwise wipe data from asset servers (rendering the current export useless, except for position, scale, etc). Allowing us to export scenes with assets would be super useful for backup and project management.

┆Issue is synchronized with this Jira Task

[Charlesc22]

Ditto for us as well. Camelgod. thanks for writing this up. You pretty much described our pains as well. If Hubs truly is to be an opened Metaverse, then the functionality you describe here is essential.

Examples of different servers where we need to move scenes between servers" Testing, Artists Design, Dev, Staging, Production, Production2 (with different configurations), Productions3..., Biz Client#1, Biz Client#2, Biz Client#3...