Rename callable_method_pointer.h to callable_mp.h and include it explicitly

This allows removing it from `class_db.h`, significantly reducing the amount of files
that include it transitively.

Also includes some include cleanup in `control.h` and `rich_text_label.h` done while
ensure they don't depend on `callable_mp`.

platform/web/javascript_bridge_singleton.cpp

@@ -35,7 +35,7 @@
 #include <emscripten.h>
 
 #ifdef PROXY_TO_PTHREAD_ENABLED
-#include "core/object/callable_method_pointer.h"
+#include "core/object/callable_mp.h"
 #endif
 
 extern "C" {