When Philippine President Rodrigo Duterte visits China later this month, he intends to raise with Chinese President Xi Jinping the contentious topic of Beijing’s activities in the South China Sea – and the 2016 UN arbitration ruling negating its territorial claims there.This has raised speculation that Manila is ready to take a harder line on its relations with Beijing, and on the South China Sea in particular, as since becoming president, Duterte has gone out of his way to embrace Beijing and…