By Andrew Chung and Nate Raymond WASHINGTON (Reuters) -The U.S. Supreme Court on Wednesday grappled with a challenge to the legality of decades-old federal requirements that give preferences to Native Americans and tribal members in the adoption or foster care placements of Native American children. The justices were hearing arguments in the challenge by a group of non-Native American adoptive families and the Republican-governed state of Texas to the Indian Child Welfare Act of 1978 after lower courts declared parts of the law unconstitutional. Democratic President Joe Biden’s administration …