Pass the pending selection to update_selections and set_selections

This helps us preserve our invariant of always having at least a pending selection in set_selections when comparing old and new cursor positions.

Co-Authored-By: Max Brunsfeld <maxbrunsfeld@gmail.com>

crates/diagnostics/src/diagnostics.rs

@@ -490,7 +490,7 @@ impl ProjectDiagnosticsEditor {
                     }
                 }
             }
-            editor.update_selections(selections, None, cx);
+            editor.update_selections(selections, None, None, cx);
             Some(())
         });