These are the best of times, these are the worst of times. Everything’s iconic, everyone’s a supermodel. Exaggeration for effect has always been fashion’s modus operandi. Words are bandied round until whatever power they were intended to convey evaporates. But, as of September 20, AppleTV+ will be doing its level best to restore lustre to at least one of fashion’s overused superlatives. “The Supermodels” is a four-part docu-series…