WASHINGTON (Reuters) - On the face of it, Universal Music Group's bid to buy a big chunk of EMI stands to make the world's leading music company an even more formidable force, combining Universal's star lineup of Lady Gaga and Rihanna with the British company's deep library of The Beatles, Pink Floyd and Katy Perry. Certainly the fierce opposition from rival Warner Music Group, consumer groups and independent music companies makes it seem that way. They have all vowed to fight it tooth and nail, telling U.S. ...