By David Morgan WASHINGTON (Reuters) -President Joe Biden on Saturday vowed to preserve a program that protects from deportation hundreds of thousands of immigrants brought to the United States as children, promising to appeal a judge's "deeply disappointing" ruling invalidating it and urging Congress to provide them a path to citizenship. U.S. District Judge Andrew Hanen on Friday ruled in favor of a group of states led by Republican-governed Texas that sued to end the Deferred Action for Childhood Arrivals (DACA) program. Hanen concluded that Democratic former President Barack Obama exceeded...