Add an OS.get_thread_caller_id() method

This can be used to print thread IDs in logs. This can make it easier
to debug multi-threaded applications.

Co-authored-by: Khaos <khaos@khaos-coders.org>

core/core_bind.h

@@ -232,6 +232,7 @@ public:
 	String get_user_data_dir() const;
 
 	Error set_thread_name(const String &p_name);
+	Thread::ID get_thread_caller_id() const;
 
 	bool has_feature(const String &p_feature) const;