By Olena Harmash KYIV (Reuters) – Ukraine has invited Chinese President Xi Jinping to participate in a planned “peace summit” of world leaders in Switzerland, a top diplomatic adviser to President Volodymyr Zelenskiy said, as Russia’s invasion approaches its second anniversary. China has close ties with Russia and has refrained from criticising its invasion of Ukraine but has also said the sovereignty and territorial integrity of all countries must be respected and has offered to help mediate in the conflict. “We are definitely inviting China to participate in the summit, at the highest level,…