Auto merge of #114757 - Urgau:transmute-with-invalid_reference_casting, r=est31

Also consider `mem::transmute` with the `invalid_reference_casting` lint

This PR extend the `invalid_reference_casting` lint with regard to the `std::mem::transmute` function.

```
error: casting `&T` to `&mut T` is undefined behavior, even if the reference is unused, consider instead using an `UnsafeCell`
  --> $DIR/reference_casting.rs:27:16
   |
LL |     let _num = &mut *std::mem::transmute::<_, *mut i32>(&num);
   |                ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
```

*I encourage anyone reviewing this PR to do so [without whitespaces](https://github.blog/2011-10-21-github-secrets/#whitespace).*

Author: bors