The LDS Church's active support of a California ballot initiative banning gay marriage so far has been mostly confined to California.     But during a special satellite broadcast from Salt Lake City tonight to LDS chapels in Utah County as well as in California, LDS authorities are expected to ask Brigham Young University students and other Californians living in Utah to participate in phone trees in support of Proposition 8, which would define marriage as exclusively between a man and a woman.     The broadcast will feature Apostles M. Russell Ballard and Quentin L. Cook and L. Whitney Clayton, ...