osx: wiring for opening a new window, but not connected to gesture yet

when I add `.tapGesture(count: 2)` to list items, this seems to block
single clicks because SwiftUI sucks. Need to find a better way to invoke
this.

osx/kordophone2/ConversationListView.swift

@@ -11,7 +11,8 @@ struct ConversationListView: View
 {
     @Binding var model: ViewModel
     @Environment(\.xpcClient) private var xpcClient
-    
+    @Environment(\.openWindow) private var openWindow
+
     var body: some View {
         List($model.conversations, selection: $model.selectedConversation) { conv in
             let isUnread = conv.wrappedValue.unreadCount > 0