Fall back to group JID if no name available

[mwild1]

Describe the bug When a group chat does not have a name set, the UI displays the default text from the storyboard editor ("very long group name...").

Instead, when no name is available, it should just show the MUC's JID in the title.

To Reproduce

1. From 'Chats' tap '+' and 'Join group chat'
2. At the bottom, tap the folder icon
3. In "Component domain" enter: groups.superxmpp.com
4. Tap back (to 'Select channel')
5. In the search box enter: codytest2
6. Tap the group chat that appears in the list
7. See the title of the chat is 'very long group name...instead ofcodytest2@groups.superxmpp.com`

Software versions:

• App Version: 1.2 (7)

• iOS version: 14.x

• iPhone model: iPhone SE 1st gen

• Server software: Snikket