allow accessing entity from intersections callback

[PROMETHIA-27]

Objective

Adds a new parameter to the callback in MoveAndSlide::intersections, to allow accessing the intersected entity.

Solution

Adds a new parameter to the relevant callback.

Testing

The change is extremely simple so as long as the logic is correct, it shouldn't need extensive testing.
I ran cargo test to try and catch all places that needed to be updated in the repo, and use the same logic in a vendored version of the function in a project and it has worked correctly so far.

I did see 4 failures in the cargo test but they seemed to be minor precision issues; float equality comparisons off by 0.0001 or so. Probably unrelated to the changes in this PR.

[Jondolf]

Thanks, LGTM once CI passes. Looks like a trivial error with a doc test missing the parameter