SDC slots not being validated against json config schema

Encountered while pairing on debugging #3390712-52: Add component variants to SDC → with @larowlan. Please credit him.

Fix + test

This looks good! Nice and simple, now with test coverage.

nod_ → closed merge request !11728

Committed and pushed 96c70753fe5 to 11.x and a9c54fca064 to 11.1.x. Thanks!

That should be in 10.5.x and 10.4.x actually, the cherry pick is not clean so needs dedicated MR

nod_ → closed merge request !11730

Committed and pushed 9256fc107f3 to 10.5.x and 9f025d2e68c to 10.4.x. Thanks!