bevy_reflect: Add DynamicTyped trait

[MrGVSV]

Objective

Thanks to #7207, we now have a way to validate at the type-level that a reflected value is actually the type it says it is and not just a dynamic representation of that type.

dyn PartialReflect values might be a dynamic type, but dyn Reflect values are guaranteed to not be a dynamic type.

Therefore, we can start to add methods to Reflect that weren't really possible before. For example, we should now be able to always get a &'static TypeInfo, and not just an Option<&'static TypeInfo>.

Solution

Add the DynamicTyped trait.

This trait is similar to DynamicTypePath in that it provides a way to use the non-object-safe Typed trait in an object-safe way.

And since all types that derive Reflect will also derive Typed, we can safely add DynamicTyped as a supertrait of Reflect. This allows us to use it when just given a dyn Reflect trait object.

Testing

You can test locally by running:

cargo test --package bevy_reflect

---

Showcase

Reflect now has a supertrait of DynamicTyped, allowing TypeInfo to be retrieved from a dyn Reflect trait object without having to unwrap anything!

let value: Box<dyn Reflect> = Box::new(String::from("Hello!"));

// BEFORE
let info: &'static TypeInfo = value.get_represented_type_info().unwrap();

// AFTER
let info: &'static TypeInfo = value.reflect_type_info();

Migration Guide

Reflect now has a supertrait of DynamicTyped. If you were manually implementing Reflect and did not implement Typed, you will now need to do so.

[SpecificProtagonist]

Very reasonable.
Might make sense to mention it in this line too.