LibGUI: Pressing Return in an editable TableView should begin editing

This matches what happens when you double-click on a cell.

Libraries/LibGUI/AbstractTableView.cpp

@@ -474,10 +474,7 @@ void AbstractTableView::doubleclick_event(MouseEvent& event)
         if (event.y() < header_height())
             return;
         if (!selection().is_empty()) {
-            if (is_editable())
-                begin_editing(selection().first());
-            else
-                activate_selected();
+            activate_or_edit_selected();
         }
     }
 }

Libraries/LibGUI/AbstractView.cpp

@@ -362,7 +362,15 @@ void AbstractView::doubleclick_event(MouseEvent& event)
     else if (!m_selection.contains(index))
         set_selection(index);
 
-    activate_selected();
+    activate_or_edit_selected();
+}
+
+void AbstractView::activate_or_edit_selected()
+{
+    if (is_editable())
+        begin_editing(selection().first());
+    else
+        activate_selected();
 }
 
 void AbstractView::context_menu_event(ContextMenuEvent& event)

Libraries/LibGUI/AbstractView.h

@@ -100,6 +100,7 @@ protected:
     void set_hovered_index(const ModelIndex&);
     void activate(const ModelIndex&);
     void activate_selected();
+    void activate_or_edit_selected();
     void update_edit_widget_position();
 
     bool m_editable { false };

Libraries/LibGUI/TableView.cpp

@@ -159,7 +159,7 @@ void TableView::keydown_event(KeyEvent& event)
         return;
     auto& model = *this->model();
     if (event.key() == KeyCode::Key_Return) {
-        activate_selected();
+        activate_or_edit_selected();
         return;
     }
     if (event.key() == KeyCode::Key_Left) {