FastAPI reference resolution

The current mechanism for resolving references through FastAPI is inconvenient/not fully functional.

I guess there are at least three different scenarios for resolving references:

1. Do not resolve, just keep the reference as a string.
2. Place the referenced section/quantity in the returned archive in its correct location (useful for deserializing python metainfo objects).
3. Resolve the reference in place (useful for environments where the python metainfo package is not available, e.g. in the GUI).

Maybe there could be an API parameter that determines the resolution mechanism? The implementation should also be able to resolve the newly added quantity references and lists of references.