Primarily a vehicle for singer-songwriter Conor Oberst, whose new album, “Conor Oberst,” came out this week, the ever-rotating group of musicians known as Bright Eyes formed when he was only 15. Unlike most celebrities who are supposed to have “grown up in the public eye” — child actors, teenage pop stars, offspring of the rich and famous — Oberst was the rare young artist who wrote his own songs and found a sizable audience while still in high school. A few years younger than the now 28-year-old Oberst, I fit right into that demographic, catching on to Bright Eyes around the turn of the millennium.