Closes #19377: Introduce config context profiles

[jeremystretch]

Closes: #19377

• Introduce the ConfigContextProfile model to hold JSON schema definitions for config contexts
• Add a profile ForeignKey on ConfigContext
• Tweak validate_schema() to not raise an error on empty values
• Tweak ModuleTypeProfile to use validate_schema() as a validator on its schema field
• Introduce SyncedDataMixin for GraphQL types for models which support data syncing

[arthanson]

Not sure if Data Source and Data file should be there - but they don't look like the completely work currently:

1. you can have both schema and data-source which I think should be one or the other.
2. adding data-file and saving will cause error
3. The UI should probably be a dropdown for the type and allow one or the other to be entered - this is different then the current Config Context entry and Config Templates - but those should probably be changed as well? (maybe separate PR)
4. data source / data file are missing from filters, tables, detail view
5. The validation I think only works against schema, not against data file.

It also doesn't validate the reverse way, i.e. if you have a profile assigned to a context then change the profile so the validation will fail on the context - Not sure if we want to put up a warning or not?

[jeremystretch]

It also doesn't validate the reverse way, i.e. if you have a profile assigned to a context then change the profile so the validation will fail on the context - Not sure if we want to put up a warning or not?

This is acceptable IMO. The schema was validated against the current profile at the time it was last modified; we can't reasonably ensure anything beyond that.