Auto merge of #74373 - lcnr:array_chunks, r=withoutboats

add `slice::array_chunks` to std

Now that #74113 has landed, these methods are suddenly usable. A rebirth of #72334

Tests are directly copied from `chunks_exact` and some additional tests for type inference.

r? @withoutboats as you are both part of t-libs and working on const generics. closes #60735

library/alloc/src/lib.rs

@@ -75,6 +75,7 @@
 #![cfg_attr(not(test), feature(generator_trait))]
 #![cfg_attr(test, feature(test))]
 #![feature(allocator_api)]
+#![feature(array_chunks)]
 #![feature(allow_internal_unstable)]
 #![feature(arbitrary_self_types)]
 #![feature(box_patterns)]

library/alloc/src/slice.rs

@@ -95,6 +95,8 @@ use crate::borrow::ToOwned;
 use crate::boxed::Box;
 use crate::vec::Vec;
 
+#[unstable(feature = "array_chunks", issue = "74985")]
+pub use core::slice::ArrayChunks;
 #[stable(feature = "slice_get_slice", since = "1.28.0")]
 pub use core::slice::SliceIndex;
 #[stable(feature = "from_ref", since = "1.28.0")]