Ensure consistency between Un/Typed AssetId and Handle

[bushrat011899]

Objective

• Fixes UntypedAssetId and AssetId<A> have different hashes for the same Asset #10629
• UntypedAssetId and AssetId (along with UntypedHandle and Handle) do not hash to the same values when pointing to the same Asset. Additionally, comparison and conversion between these types does not follow idiomatic Rust standards.

Solution

• Added new unit tests to validate/document expected behaviour
• Added trait implementations to make working with Un/Typed values more ergonomic
• Ensured hashing and comparison between Un/Typed values is consistent
• Removed From trait implementations that panic, and replaced them with TryFrom

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Changelog

• Ensured Handle::<A>::hash and UntypedHandle::hash will produce the same value for the same Asset
• Added non-panicing Handle::<A>::try_typed
• Added PartialOrd to UntypedHandle to match Handle<A> (this will return None for UntypedHandles for differing Asset types)
• Added TryFrom<UntypedHandle> for Handle<A>
• Added From<Handle<A>> for UntypedHandle
• Removed panicing From<Untyped...> implementations. These are currently unused within the Bevy codebase, and shouldn't be used externally, hence removal.
• Added cross-implementations of PartialEq and PartialOrd for UntypedHandle and Handle<A> allowing direct comparison when TypeId's match.
• Near-identical changes to AssetId and UntypedAssetId

Migration Guide

If you relied on any of the panicing From<Untyped...> implementations, simply call the existing typed methods instead. Alternatively, use the new TryFrom implementation instead to directly expose possible mistakes.

Notes

I've made these changes since Handle is such a fundamental type to the entire Asset ecosystem within Bevy, and yet it had pretty unclear behaviour with no direct testing. The fact that hashing untyped vs typed versions of the same handle would produce different values is something I expect to cause a very subtle bug for someone else one day.

I haven't included it in this PR to avoid any controversy, but I also believe the typed_unchecked methods should be removed from these types, or marked as unsafe. The texture_atlas example currently uses it, and I believe it is a bad choice. The performance gained by not type-checking before conversion would be entirely dwarfed by the act of actually loading an asset and creating its handle anyway. If an end user is in a tight loop repeatedly calling typed_unchecked on an UntypedHandle for the entire runtime of their application, I think the small performance drop caused by that safety check is a form of cosmic justice reasonable.

[KirmesBude]

Can not comment on the implementation (looks fine though), but I ran into this mismatch of (untyped) TypeIds and these changes fix the problem. Thanks :)

Is it possible to separate the underlying change from the breaking changes for potential inclusion in 0.12.1? (Whether that is something actually worth pursuing, I will leave up to someone else, but I would appreciate it :D)

[alice-i-cecile]

I think that cleaning up the trait impls using the Borrow trait is nice, but we can do that in a different PR if you prefer.

On board with fixing this, and the code and tests are good.