Objects API reg.: Handle object types where `allowGeometry` is false

[Viicos]

Some Objecttypes disallow setting geometry info. Currently, every objecttype is assumed to accept geometry.

https://github.com/open-formulieren/open-forms/pull/4102 is an attempt to take this into account, but was too hard to implement.

https://github.com/open-formulieren/open-forms/pull/4046 is an alternative implementation.