remove iter_unsafe/iter_many_unsafe/iter_combinations_unsafe from Query

[Victoronz]

Objective

The unsafe versions of iter, iter_many and iter_combinations on Query have identical signatures and implementations to their safe mutable versions.

Solution

Remove them.

Testing

They don't appear in tests.

Changelog

Removed the iter_unsafe, iter_many_unsafe and iter_combinations_unsafe methods on Query.

Migration Guide

Uses of iter_unsafe, iter_many_unsafe and iter_combinations_unsafe methods on Query can be safely replaced with their mutable equivalents.

[mnmaita]

@Victoronz what does this PR need to be undrafted? Also, unsure if these should be handled as a deprecation and then a removal on a following release, but I'll leave this to maintainers. Thanks!

[Victoronz]

I misread their signature and thought I could just remove them, and when I realized, I drafted this PR to think about whether it would still make sense to remove them. Now I think that they do have uses that can't be covered by the other methods, so this PR is best closed. (That being said, the engine itself doesn't use them, and a Github search only brought up about a dozen uses in the wild, and only part of those followed the Safety contract properly, so it might still make sense to remove them in the future)