This partially reverts commit 4b5b6cb,
reversing some changes made to 62b3624.

Co-Authored-By: Ralf Jung <post@ralfj.de>
Co-Authored-By: Oliver Scherer <github35764891676564198441@oli-obk.de>

Avoids having to repeat InterpErrorInfo { .. }

mutability

as `Applicability::Unspecified`

…asKalbertodt

Add `RefCell::take`

Add `RefCell::take` to match `Cell` and `Option`.
I also changed a couple of calls to `.replace` to `.take`.

Tracking issue is rust-lang#71395.

This is my first contribution, please tell me if there's anything I could improve, thanks!

Suggest deref when coercing `ty::Ref` to `ty::RawPtr` with arbitrary mutability

Fixes rust-lang#71676
1. Implement dereference suggestion when coercing `ty::Ref` to `ty::RawPtr` with arbitrary mutability.
2. Extract the dereference steps into `deref_steps()`, which removes all the `use` and `pub` noise introduced by last PR rust-lang#71540, and makes the code more readable.
3. Use the `remove_prefix()` closure which makes the prefix removal more readable.
4. Introduce `Applicability` as a return value of `check_ref` to suggest `Applicability::Unspecified` suggestion.

**Special**: I found it is not possible to genereate `Applicability::MachineApplicable` suggestion for situation like this:
```rust
use std::ops::Deref;
use std::ops::DerefMut;
struct Bar(u8);
struct Foo(Bar);
struct Emm(Foo);
impl Deref for Bar{
    type Target = u8;
    fn deref(&self) -> &Self::Target {
        &self.0
    }
}
impl Deref for Foo {
    type Target = Bar;
    fn deref(&self) -> &Self::Target {
        &self.0
    }
}
impl Deref for Emm {
    type Target = Foo;
    fn deref(&self) -> &Self::Target {
        &self.0
    }
}
impl DerefMut for Bar{
    fn deref_mut(&mut self) -> &mut Self::Target {
        &mut self.0
    }
}
impl DerefMut for Foo {
    fn deref_mut(&mut self) -> &mut Self::Target {
        &mut self.0
    }
}
impl DerefMut for Emm {
    fn deref_mut(&mut self) -> &mut Self::Target {
        &mut self.0
    }
}
fn main() {
    let a = Emm(Foo(Bar(0)));
    let _: *mut u8 = &a; //~ ERROR mismatched types
}
```
We may suggest `&mut ***a` here, but the `a` is not declared as mutable variable. And also when processing HIR, it's not possible to check if `a` is declared as a mutable variable (currently we do borrow checking with MIR). So we cannot ensure that suggestion when coercing immutable reference to mutable pointer is always machine applicable. Therefore I added a `Applicability` return value in `check_ref()`. And move the `immutable reference -> mutable pointer` situation into a sperate test file without `run-rustfix`. (It seems that `run-rustfix` will also adopt `Applicability::Unspecified` suggestion, which is strange)

…uillaumeGomez

Add long error explanation for E0539

since this error is similar to [E0551](https://github.com/rust-lang/rust/blob/master/src/librustc_error_codes/error_codes/E0551.md) most of the content was copied from it. part of rust-lang#61137.