Rollup merge of #110823 - compiler-errors:tweak-await-span, r=b-naber

Tweak await span to not contain dot

Fixes a discrepancy between method calls and await expressions where the latter are desugared to have a span that *contains* the dot (i.e. `.await`) but method call identifiers don't contain the dot. This leads to weird suggestions suggestions in borrowck -- see linked issue.

Fixes #110761

This mostly touches a bunch of tests to tighten their `await` span.

Author: matthiaskrgr

core/src/future/into_future.rs

@@ -99,6 +99,7 @@ use crate::future::Future;
 /// }
 /// ```
 #[stable(feature = "into_future", since = "1.64.0")]
+#[rustc_diagnostic_item = "IntoFuture"]
 pub trait IntoFuture {
     /// The output that the future will produce on completion.
     #[stable(feature = "into_future", since = "1.64.0")]