Decouple EditorInterface from EditorPlugin

- Simplify some includes in the process.
- Also exposes EditorInterface.movie_maker_enabled as a property.

editor/editor_node.cpp

@@ -75,6 +75,7 @@
 #include "editor/editor_folding.h"
 #include "editor/editor_help.h"
 #include "editor/editor_inspector.h"
+#include "editor/editor_interface.h"
 #include "editor/editor_layouts_dialog.h"
 #include "editor/editor_log.h"
 #include "editor/editor_native_shader_source_visualizer.h"
@@ -7901,11 +7902,6 @@ EditorNode::EditorNode() {
 		print_verbose("Asset Library not available (due to using Web editor, or SSL support disabled).");
 	}
 
-	// Add interface before adding plugins.
-
-	editor_interface = memnew(EditorInterface);
-	add_child(editor_interface);
-
 	// More visually meaningful to have this later.
 	raise_bottom_panel_item(AnimationPlayerEditor::get_singleton());