“Hamlet: The Bad Quarto”, a script that predates the best-loved published Folio, employs some names, phrasing and layering that resemble an early draft, before the Bard really got going on eloquence and rhythms. Yet, taken for all, “The Bad Quarto” doesn’t seem so very different by comparison. Rare in presentation, it is an exhilarating treat to experience the play now onstage at the Rauh Studio Theatre in Oakland, presented by director Jeremy Seghers with a youthful cast, led by Ayden Freed.