The Grand Prix went to Spike Lee’s “BlacKkKlansman,” an American racial drama that just about pops with relevance. From the lofty heights at the top of the carpet, Cannes carried on business as usual. Yet that didn’t stop a great many people, throughout the festival, from asking: Has Cannes lost its luster, its excitement, its relevance? Has its status as the world’s most prestigious and sexy and important film festival been dimmed? Has it been undermined by a perfect storm of elements, from the rise of Netflix to the power of awards season? To put it in the most blunt terms possible: Are the great films now playing somewhere else?