UIProfile: name constants as they appear in the MC user-facing settings

I think these names are stupid, but it'll be easier for people to figure out what they refer to if they match the client-sided naming.

src/pocketmine/network/mcpe/protocol/types/UIProfile.php

@@ -29,6 +29,6 @@ final class UIProfile{
 		//NOOP
 	}
 
-	public const DESKTOP = 0;
+	public const CLASSIC = 0;
-	public const MOBILE = 1;
+	public const POCKET = 1;
 }