While serenading locals with charming renditions of Celine Dion for passers-by outside of the movie theater in her hometown of Pomona, Calif., 11-year-old singer Denisse Lara could never have imagined her commanding falsetto would eventually impress such grand divas as Barbara Streisand and Cher. "Back then I didn't know who they were," recalls Lara, now 23, of the icons. "I was just singing and having fun." Soon after being discovered outside that theater, Denisse found herself singing for the divas…