PixelPaint: Enable more text tool keyboard shortcuts

This commit allows the text tool's internal TextEditor component to
handle keyboard shortcuts that would normally be handled by menu
actions.

The shortcuts that can now be used are: cut, copy, paste, undo, redo
and select all.

Userland/Applications/PixelPaint/Tools/TextTool.h

@@ -22,6 +22,7 @@ class TextToolEditor : public GUI::TextEditor {
 public:
     virtual ~TextToolEditor() override = default;
     virtual void handle_keyevent(Badge<TextTool>, GUI::KeyEvent&);
+    NonnullRefPtrVector<GUI::Action> actions();
 
 protected:
     TextToolEditor();