Auto merge of #16330 - zheylmun:master, r=Veykril

minor: Mark unresolved associated item diagnostic as experimental

Per #16327 unresolved associated item has false positives.  Mark the diagnostic as experimental until this is more dependable.

crates/ide-diagnostics/src/handlers/unresolved_assoc_item.rs

@@ -13,6 +13,7 @@ pub(crate) fn unresolved_assoc_item(
         "no such associated item",
         d.expr_or_pat.clone().map(Into::into),
     )
+    .experimental()
 }
 
 #[cfg(test)]