Rollup merge of #140066 - thaliaarchi:const-array-as-mut-slice, r=jhpratt

Stabilize `<[T; N]>::as_mut_slice` as `const`

This is trivial and has no design questions.

Tracked in https://github.com/rust-lang/rust/issues/133333.

r? libs-api

library/core/src/array/mod.rs

@@ -588,7 +588,7 @@ impl<T, const N: usize> [T; N] {
     /// Returns a mutable slice containing the entire array. Equivalent to
     /// `&mut s[..]`.
     #[stable(feature = "array_as_slice", since = "1.57.0")]
-    #[rustc_const_unstable(feature = "const_array_as_mut_slice", issue = "133333")]
+    #[rustc_const_stable(feature = "const_array_as_mut_slice", since = "CURRENT_RUSTC_VERSION")]
     pub const fn as_mut_slice(&mut self) -> &mut [T] {
         self
     }