`transmutes_expressible_as_ptr_casts` does not detect reference-to-usize transmutes

Summary

Clippy by default lints against transmuting raw pointers to usize. However, it does not lint against transmuting references to usize. Both of these transmutes are highly questionable so it'd be good to lint them all.

Lint Name

transmutes_expressible_as_ptr_casts

Reproducer

I tried this code:

fn main() { unsafe {
    let _x: usize = std::mem::transmute(&0);
}}

I expected to see this happen: clippy should complain about the transmute.

Instead, this happened: clippy remains silent.

Version

Current playground

Start at the transmutes_expressible_as_ptr_casts lint and reproduce the reference-to-usize example from the issue. Done means the lint reports this transmute, while continuing to handle the raw-pointer case already described.