By Claudia Cristoferi MILAN (Reuters) -First quarter sales at Italian fashion group Moncler jumped by 60%, beating once again analysts expectations, driven by a strong performance in China that offset new Covid-19 restrictions, as well as a surge in U.S. and online sales. The luxury outwear maker will hold an investor presentation on Thursday, its first since the outbreak of the coronavirus pandemic and the acquisition of streetwear brand Stone Island in 2020. Overall revenues for the three months to end March totalled 589.9 million euros ($622 million), up 60% from the same period a year ago …