Reorganize some of bevy_reflect's exports into their respective modules

[LikeLakers2]

Objective

• Re-organize bevy_reflect's exports to de-clutter the crate root #22321

Solution

Do it

Testing

cargo clippy and CI.

[it-me-joda]

Seems like some pretty nice and thorough reorganization. Aside from cleanliness, is there an additional benefit you are trying to capture with moving things around?

[janhohenheim]

I didn't inspect these tooooooo deeply, but it looks good :)

[LikeLakers2]

[@it-me-joda] Aside from cleanliness, is there an additional benefit you are trying to capture with moving things around?

The main point is to make it clear what items belong to what type of reflected item, which in turn helps to avoid overwhelming users.

So no, not really - the cleanliness is the main point, that ends up causing other (beneficial) effects.

[LikeLakers2]

Per my request, MrGVSV has been requested to review this, as he's the reflection SME.

Though if any maintainers want to merge without his review, feel free. I just think, since I've been communicating with him a bit while planning and making this PR, it'd be worth requesting his review.

[LikeLakers2]

[@janhohenheim] I didn't inspect these tooooooo deeply, but it looks good :)

In case you want to inspect more deeply, here's the files you'd be most interested in:

• crates/bevy_reflect/derive/src/derive_data.rs (code change to account for the new typepaths)
• crates/bevy_reflect/derive/src/from_reflect.rs (code change to account for the new typepaths)
• release-content/migration-guides/bevy_reflect_reorganization.md (migration guide)

Pretty much everything else is changes to typepaths themselves (usually use statements), plus basic docs for the newly-exposed modules. Well, and publicly exposing the modules.