Extract editor run toolbar into its own component

- Simplify and update its logic.
- Simplify EditorScript.
- Improve EditorNode and other relevant includes.
- Fix scene-based path in the movie writer when
reloading a scene.

editor/plugins/script_text_editor.cpp

@@ -38,6 +38,7 @@
 #include "editor/editor_node.h"
 #include "editor/editor_scale.h"
 #include "editor/editor_settings.h"
+#include "scene/gui/rich_text_label.h"
 #include "scene/gui/split_container.h"
 
 void ConnectionInfoDialog::ok_pressed() {