Migrate bevy_transform to required components

[ecoskey]

The first step in the migration to required components! This PR removes GlobalTransform from all user-facing code, since it's now added automatically wherever Transform is used.

Testing

• None of the examples I tested were broken, and I assume breaking transforms in any way would be visible everywhere

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Changelog

• Make Transform require GlobalTransform
  - Remove GlobalTransform from all engine bundles
• Remove in-engine insertions of GlobalTransform and TransformBundle
• Deprecate TransformBundle
• update docs to reflect changes

Migration Guide

Replace all insertions of GlobalTransform and/or TransformBundle with Transform alone.

[JMS55]

Missed MaterialMeshletMeshBundle

[ecoskey]

oops

[alice-i-cecile]

I'm in favor of this. The opposite direction (GlobalTransform -> Transform) is much more intrusive and interferes with our plans to split apart Transform (#1275), but I think that this is nearly universally desirable.

[TrialDragon]

The file /errors/B0004.md contains rust doc which uses Transform bundles and should be updated to use this change. (It's why CI is failing). Otherwise, looks good.

[ecoskey]

The file /errors/B0004.md contains rust doc which uses Transform bundles and should be updated to use this change. (It's why CI is failing). Otherwise, looks good.

It seems [the guidance to fix] this error would be obsolete or inconsistent with the required components workflow. Should we block this PR on updating things like this or leave that to a later documentation pass?

[TrialDragon]

It seems [the guidance to fix] this error would be obsolete or inconsistent with the required components workflow. Should we block this PR on updating things like this or leave that to a later documentation pass?

I'm not entirely sure it would be? I don't think required components add components to the parent entities, do they? Either way, this can be a follow-up if it is actually redundant in a post required components world.

(Also, the bundle docs seem to be having an issue with GlobalTransform no longer being in scope).

[ecoskey]

I don't think I expressed that clearly lol. What I meant was that we're going to need to update a lot of docs anyway for the new workflow, so I was wondering if it might make more sense to do a later pass rather than make a lot of changes to that page just because it referenced TransformBundle. But doctests need to pass, so I can fix it in the morning :)

[ecoskey]

Fixed the docs. They're (specifically errors/B0004.md) in a bit of a weird half-way state since we're intending to nuke SpatialBundle also, but they do accurately reflect the state of things in between PRs.

[alice-i-cecile]

This LGTM, but I'm not going to merge until we have consensus from @cart :) Thanks for tackling this!

[alice-i-cecile]

@ecoskey once CI is passing, please ping me. We're ready to proceed with this work :) See this message from Cart on Discord.

[alice-i-cecile]

Thank you to everyone involved with the authoring or reviewing of this PR! This work is relatively important and needs release notes! Head over to bevyengine/bevy-website#1699 if you'd like to help out.