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/android/os_android.cpp

@@ -43,13 +43,13 @@
 #include "core/extension/gdextension_manager.h"
 #include "core/input/input.h"
 #include "core/io/xml_parser.h"
+#include "core/object/callable_mp.h"
 #include "core/os/main_loop.h"
 #include "core/os/os.h"
 #include "core/profiling/profiling.h"
 #include "drivers/unix/dir_access_unix.h"
 #include "drivers/unix/file_access_unix.h"
 #ifdef TOOLS_ENABLED
-#include "core/object/callable_method_pointer.h"
 #include "editor/editor_node.h"
 #include "editor/run/game_view_plugin.h"
 #endif