June’s arrival ought to offer a reprieve after a shockingly busy May art fair calendar packed to the rafters with events—and auctions—both in and outside of New York City. But if the June art fair calendar is only refreshingly light because of Art Basel’s global dominance, at least the next best thing to a month off is a few weeks on the Rhine. Beyond Art Basel, the sundry Swiss satellite fairs are the order of the day this month, and we’re not …