Include titles for JSON Schema properties

[TimothyBlynJacobs]

JSON Schema supports a title property that can hold a user-readable label for the property. This would be incredibly helpful in building generated documentation and user interfaces.

[schlessera]

I agree, this would be very useful for automated UI generation and documentation.

However, without something like #41305, it will also double the already exorbitant number of calls to translate(). Something to keep in mind before merging, as it will probably have a big negative impact on performance with the current codebase.

[joehoyle]

Interesting, perhaps we just missed this in the initial JSON schema pass! Seems like a good addition for UIs and the like, though as @schlessera we should probably do some testing around this. I imagine we might need to do a fresh pass to as we may have new properties too.