UI tests: implement add contact from the chat in community channel

[jrainville]

Description

The scenario The user can add a contact from the chat was removed because we no longer support public chats.

Re-implement it in the context of a community channel.

[jrainville]

This one is harder to do, because we need a test where two accounts are in the same community, but not contacts. Also, we'd need to do a cleanup since we'd keep the data folder.

Putting this on pause as it's not worth the effort