msglist: Colorize channel icon in the app bar, following Figma#1524

gnprice merged 1 commit intozulip:mainzulip/zulip-flutter:mainfrom

chrisbobbe:pr-colorize-msglist-app-bar-channel-iconchrisbobbe/zulip-flutter:pr-colorize-msglist-app-bar-channel-iconCopy head branch name to clipboard