WASHINGTON (Reuters) - U.S. Republicans in Congress are lining up behind legislation that critics say would roll back protections for transgender people, setting a playbook for action on a divisive social issue should they take control of Congress this fall. Republicans in the House of Representatives have introduced a bill that would block federal funding to colleges where transgender women are allowed to participate in sports with cisgender women. A separate bill would allow transgender people to sue medical personnel who helped them transition as minors. Another bill would block funding to schools that disobey state laws regarding "materials harmful...