Rollup merge of #90644 - est31:const_swap, r=Mark-Simulacrum

Rollup merge of #90644 - est31:const_swap, r=Mark-Simulacrum

Extend the const swap feature

Adds the `const_swap` feature gate to three more swap functions. cc tracking issue #83163

```Rust
impl<T> [T] {
    pub const fn swap(&mut self, a: usize, b: usize);
    pub const unsafe fn swap_unchecked(&mut self, a: usize, b: usize);
}
impl<T: ?Sized> *mut T {
    pub const unsafe fn swap(self, with: *mut T);
}