Rollup merge of #93613 - crlf0710:rename_to_async_iter, r=yaahc

Move `{core,std}::stream::Stream` to `{core,std}::async_iter::AsyncIterator`

Following amendments in https://github.com/rust-lang/rfcs/pull/3208/.

cc #79024
cc ``@yoshuawuyts`` ``@joshtriplett``

library/core/src/lib.rs

@@ -305,6 +305,8 @@ pub mod ops;
 pub mod any;
 pub mod array;
 pub mod ascii;
+#[unstable(feature = "async_iterator", issue = "79024")]
+pub mod async_iter;
 pub mod cell;
 pub mod char;
 pub mod ffi;
@@ -316,8 +318,6 @@ pub mod panic;
 pub mod panicking;
 pub mod pin;
 pub mod result;
-#[unstable(feature = "async_stream", issue = "79024")]
-pub mod stream;
 pub mod sync;
 
 pub mod fmt;