Add support for schemaFile

[h3adache]

schemaFile was added to zed in authzed/zed#455 and spicedb in authzed/spicedb#2206.

But importing a zed yaml with it doesn't work.

It would be nice to be able to support this new syntax.

[tstirrat15]

How would that work? The import functionality is an uploaded file, which isn't going to have enough context to pull in a separate file.

[noseworthy]

Yeah, that is tricky. Maybe the ability to upload schemas and validation files separately if necessary? Like, if a validation file includes the schemaFile directive, the user is prompted a second time to upload the associated schema file?

Sounds/feels clunky though. But it'd be great to have this feature as I think having the schema separated from different validation files with specific purposes is super useful. Hopefully you folks can figure out a decent UX for getting this to work with the playground.