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.