"soft" remove EntityRef::get_unchecked_mut

[BoxyUwU]

Objective

EntityRef::get_unchecked_mut existing is sort of "in conflict" with the idea that the &World in EntityRef is "truly" shared readonly rather than doing interior mutable shenanigans like query (see #5588). So remove it 🤔

I am a bit apprehensive about 'just' removing this method since I'm not convinced we have enough interior mutability/world splitting primitives in bevy rn to cover all of the uses that this method might have. Particularly I think you could use this method to accomplish a wildly unsafe unchecked "entity granular borrowck" vs the way Query works which is "archetype component id granular" and we don't have an API to do that in bevy atm.

Unfortunately (and somewhat ironically) Query::get_component_unchecked_mut uses this fn so instead of outright removing, it's just been made pub(crate). I am not sure if it is better to instead call the "internal" component getter methods in entity_ref.rs instead of this.

need to think about this all a bit more before this is merged I think

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Changelog

• EntityRef::get_unchecked_mut has been removed

Migration Guide

Try rearchitecting your code to not require this ( I know not very helpful ), if you have a good use case please share what it is so that it can help inform designing a good API to replace EntityRef::get_unchecked_mut :)

[BoxyUwU]

Closing this in favor of #6404 which introduces an InteriorMutableWorld type that can be used by callers of this method in a more principled way, allowing us to fully remove this method instead of privating