The TikTok logo is pictured outside the company's U.S. head office in Culver City, California, U.S., September 15, 2020. REUTERS/Mike Blake/File Photo WASHINGTON, Aug 7 (Reuters) - Two tech groups on Monday backed TikTok Inc in its lawsuit seeking to block enforcement of a Montana state ban on use of the short video sharing app before it takes effect on Jan. 1. NetChoice, a national trade association that includes major tech platforms, and Chamber of Progress, a tech-industry coalition, said in a joint court filing that "Montana's effort to cut Montanans off from the global network of TikTok users ignores...