⚛️ Initial state generation using KSP

[heytherewill]

Summary

This adds state generation capabilities using KSP, similar to what we already have for actions.

Relationships

Point 3 of #60

Technical considerations

We should create tests that verify more complex scenarios and we should start using these in the samples ASAP to make sure they work in the wild and not only in a vacuum, but the existing tests cover simple mapping, children having different property names because they have more context and nested properties, which, from experience, covers most use cases.

The @ParentPath property is stringly types, but you do get a decent compiler error if the parent property changes, so it's still fairly safe!

Review pointers

Make sure that the code is readable (or: as readable as KSP can be since there's a lot of shenanigans).

Merge permissions

Get this in ASAP as possible.