fix(Communities): make creating channels work again

Very similar to #1986, we're trying to access the `activeCommunity`
property on the `chatsModel` object, which doesn't have such a property
anymore every since we've moved communities into its own view.
This causes errors when trying to create channels.

This commit fixes this bug by ensuring `activeCommunity` is accessed
from `chatsModel.communities` instead.

ui/app/AppLayouts/Chat/CommunityColumn.qml

@@ -71,7 +71,7 @@ Item {
                     icon.source: "../../img/hash.svg"
                     icon.width: 20
                     icon.height: 20
-                    onTriggered: openPopup(createChannelPopup, {communityId: chatsModel.activeCommunity.id})
+                    onTriggered: openPopup(createChannelPopup, {communityId: chatsModel.communities.activeCommunity.id})
                 }
 
                 Action {