lsp: Support on-type formatting request with newlines (#44882)

We called out to `request_on_type_formatting` only in handle_input
function, but newlines are actually handled by editor::Newline action.

Closes #12383

Release Notes:

- Added support for on-type formatting with newlines.

crates/editor/src/editor.rs

@@ -5018,6 +5018,9 @@ impl Editor {
 
             this.change_selections(Default::default(), window, cx, |s| s.select(new_selections));
             this.refresh_edit_prediction(true, false, window, cx);
+            if let Some(task) = this.trigger_on_type_formatting("\n".to_owned(), window, cx) {
+                task.detach_and_log_err(cx);
+            }
         });
     }
 
@@ -5082,6 +5085,9 @@ impl Editor {
                 }
             }
             editor.edit(indent_edits, cx);
+            if let Some(format) = editor.trigger_on_type_formatting("\n".to_owned(), window, cx) {
+                format.detach_and_log_err(cx);
+            }
         });
     }
 
@@ -5144,6 +5150,9 @@ impl Editor {
                 }
             }
             editor.edit(indent_edits, cx);
+            if let Some(format) = editor.trigger_on_type_formatting("\n".to_owned(), window, cx) {
+                format.detach_and_log_err(cx);
+            }
         });
     }
 
@@ -5454,7 +5463,7 @@ impl Editor {
         window: &mut Window,
         cx: &mut Context<Self>,
     ) -> Option<Task<Result<()>>> {
-        if input.len() != 1 {
+        if input.chars().count() != 1 {
             return None;
         }