Schema generation for Spring starter (declarative config)

[zeitlinger]

Is your feature request related to a problem? Please describe.

The spring starter schema is currently hand written.

For declarative config, this should be generated if possible.

Maybe the new schema should become the standard with 3.0?

Describe the solution you'd like

Describe alternatives you've considered

No response

Additional context

No response

[zeitlinger]

See the ideas in #14082