Editor: Cleanup some includes dependencies

Removes some unnecessary includes from `editor_node.h`, and instead add
those where they're used.

Removes unnecessary `editor_node.h` includes in various editor classes.

Renames `dynamicfont` to `dynamic_font` in a couple files.

Misc cleanup while jumping through that rabbit hole.

editor/plugins/input_event_editor_plugin.cpp

@@ -30,8 +30,6 @@
 
 #include "input_event_editor_plugin.h"
 
-#include "editor/editor_node.h"
-
 void InputEventConfigContainer::_bind_methods() {
 }