There are two new names to add to a short list of candidates to become the next owner of the Celtics. Current Celtics limited partner Robert Hale, a fixture on the Forbes’s annual list of wealthiest Americans, said Friday he has “keen interest” in exploring a bid. Mark Bezos, founding partner of HighPost Capital private equity group and half-brother of Amazon founder Jeff Bezos, has expressed interest as well, an industry source told the Globe.