Auto merge of #112431 - Urgau:cast_ref_to_mut_improvments, r=Nilstrieb

Improve `invalid_reference_casting` lint

This PR is a follow-up to rust-lang/rust#111567 and rust-lang/rust#113422.

This PR does multiple things:
 - First it adds support for deferred de-reference, the goal is to support code like this, where the casting and de-reference are not done on the same expression
    ```rust
    let myself = self as *const Self as *mut Self;
    *myself = Self::Ready(value);
    ```
 - Second it does not lint anymore on SB/TB UB code by only checking assignments (`=`, `+=`, ...) and creation of mutable references `&mut *`
 - Thirdly it greatly improves the diagnostics in particular for cast from `&mut` to `&mut` or assignments
 - ~~And lastly it renames the lint from `cast_ref_to_mut` to `invalid_reference_casting` which is more consistent with the ["rules"](rust-lang/rust-clippy#2845) and also more consistent with what the lint checks~~ *rust-lang/rust#113422

This PR is best reviewed commit by commit.

r? compiler

tests/fail/both_borrows/illegal_write1.rs

@@ -1,6 +1,8 @@
 //@revisions: stack tree
 //@[tree]compile-flags: -Zmiri-tree-borrows
 
+#![allow(invalid_reference_casting)]
+
 fn main() {
     let target = Box::new(42); // has an implicit raw
     let xref = &*target;

tests/fail/stacked_borrows/illegal_write3.rs

@@ -1,3 +1,5 @@
+#![allow(invalid_reference_casting)]
+
 fn main() {
     let target = 42;
     // Make sure raw ptr with raw tag cannot mutate frozen location without breaking the shared ref.