Add particle type definition format and loader

### I am planning on implementing this myself

Yes

### Describe your request

There should be a way for `ParticleType`s (and their hierarchies) to be defined in an asset format that can be hot reloaded when helper authors are creating custom entities.

I currently have a prototype particle loader class that reads from a yaml file, using anchors and aliases to define particle type inheritance. I’m also working on a particle editor for writing these files, but this would be implemented as a separate mod or standalone application.

### Additional context

_No response_