Add generic templates for DataResponse and JSONResponse

[provokateurin]

Summary

Add templates to indicate generic type. Not required, but very useful for OpenAPI.

Checklist

• Code is properly formatted
• Sign-off message is added to all commits
• Tests (unit, integration, api and/or acceptance) are included
• Screenshots before/after for front-end changes
• Documentation (manuals or wiki) has been updated or is not required
• Backports requested where applicable (ex: critical bugfixes)

[come-nc]

This adds a new constraints that one cannot use setData with another type than what was used in the constructor. No idea if this is a problem or not.

[ChristophWurst]

this weakens the type. before it was an array or object. now it can be anything

[provokateurin]

Waiting on a solution for #36513 before continuing since this change might not be needed after all.

[provokateurin]

I just realized this isn't possible, since psalm will complain about missing template types in every place that isn't updated.