new-chat-dialog: Implement New Message Flow
/cc @sam.hewitt
/cc @alexander.mikhaylenko if/when you are back: any handy way to merge 3 listboxes with content style (You, the list of selected items, and the "Add members from..." are 3 listboxes)
/cc @sam.hewitt
/cc @alexander.mikhaylenko if/when you are back: any handy way to merge 3 listboxes with content style (You, the list of selected items, and the "Add members from..." are 3 listboxes)