Fix definition of vid_ranges in VLANGroup so it shows up in the OpenAPI schema

[mraerino]

Fixes: #17488

The OpenAPI schema for vid_ranges cannot automatically be discovered by drf-spectacular since it's a custom serializer with no fields. Therefore we need to manually provide the OpenAPI schema for the type we expect to see in requests and responses.

On top of that there is a bug in drf-spectacular that required the workaround with the custom list class (tfranzel/drf-spectacular#1353).

[jeremystretch]

@mraerino did you see the comment here regarding the use of extend_schema_field() on a serializer (versus a field)? I suspect a more prudent solution might be to rewrite IntegerRangeSerializer to use IntegerField, though I'm not sure of the specifics.

[mraerino]

yeah i saw. i think this is likely a little bit more complex and i wanted to get this bug fix out quickly so people can use the API again.

I can look into improving this in another PR, if you're ok with that?

[github-actions]

This PR has been automatically marked as stale because it has not had recent activity. It will be closed automatically if no further action is taken.

[mraerino]

@jeremystretch i changed the implementation to use a schema extension instead of an annotation, as recommended by the spectacular devs.

I don't think using IntegerField will work since we have an array of integers in an array and 2 dimensions cannot be modelled without a custom serializer

[arthanson]

@mraerino Can you please rebase this to main

[mraerino]

@mraerino Can you please rebase this to main

done!