Improve includes of EditorNode (and everything else)

Also start organizing editor-specific GUI components
into a dedicated folder, `editor/gui`.
Also move `editor_file_server` next to the rest of debugger classes.

editor/editor_feature_profile.cpp

@@ -32,12 +32,12 @@
 
 #include "core/io/dir_access.h"
 #include "core/io/json.h"
-#include "editor/editor_file_dialog.h"
 #include "editor/editor_node.h"
 #include "editor/editor_paths.h"
 #include "editor/editor_property_name_processor.h"
 #include "editor/editor_scale.h"
 #include "editor/editor_settings.h"
+#include "editor/gui/editor_file_dialog.h"
 
 const char *EditorFeatureProfile::feature_names[FEATURE_MAX] = {
 	TTRC("3D Editor"),