Add an OS.get_processor_name() method

This method can be used to get the CPU model name.
It can be used in conjunction with
`RenderingServer.get_video_adapter_name()` and
`RenderingServer.get_video_adapter_vendor()` for annotating benchmarks
and automatic graphics quality configuration.

core/core_bind.h

@@ -218,6 +218,7 @@ public:
 	bool is_stdout_verbose() const;
 
 	int get_processor_count() const;
+	String get_processor_name() const;
 
 	enum SystemDir {
 		SYSTEM_DIR_DESKTOP,