Support loading self contained 'Asset bundles'

This would be similar to Addressable asset system in Unity: https://docs.unity3d.com/Packages/com.unity.addressables@0.4/manual/index.html

The idea would there would a self contained bundle that could be loaded by the engine and the scenes, assets, scripts are added to the existing apps system (asset registry, scene registry, etc)

We have some of this functionality with the current .tar bundle loader but that assumes the assets have been registered to the registry already.

Having a system where new data bundles can added as self contained files could help with larger applications or games where content is updated and controlled by servers/CMS system. It could also help with splitting and managing larger projects

Eg. a game can have live events for valentines day, easter etc. Rather than uploading a whole new build, developers can have bundles that have all the assets needed for the event and it would be downloaded as part of the live event via control on the server side without needing to update the core build.

Another example would be for a car visualiser where each model is a separate bundle via CMS where it can be managed separately from the main project

The issue names the current .tar bundle loader, asset registry, and scene registry; start by tracing how that loader registers assets and scenes. Done would mean a self-contained bundle can load its assets, scenes, and scripts into the existing systems, but the issue does not identify implementation files or tests.