chgserver: make _renewui load repo and command line configs Before this patch, there is no way to load repo config in chgserver. This patch revised _renewui to let it load repo config and take command line flags passed into consideration. The _renewui logic is not ideal at present because it's very tricky to know what should copy and what should not from the old ui object to the new one. This is partially because the current ui and config object design is not ideal. In the future, we may want to avoid all ui or config copies.