Enable encryption automatically for new users and new group chats created

[tiffrobo]

When you start a new group or are a new user auto enable encryption.

• Leave the visibility of settings UI toggle to be enabled by the user

[N-Pex]

Ok, so turns out we had previously overridden upstream to start groups in "plaintext". Now, I removed that code to have the same logic as upstream, which is "if we have keys for any of the room occupants, we can do omemo", see bestTransportSecurity in OTRMPPRoom.swift.

@n8fr8 Good enough?

[n8fr8]

Yes, great!

[tiffrobo]

@N-Pex So what should I see as a user in the UI? Will I see the Group Encryption option with the toggle to 'on' in every new group as a new user? Or is it 'enabled' but in order to see the UI I must go into my settings and turn the master toggle on?

Right now I don't see any UI in group chat until I go into my settings and enable it from there. However, once I do, in my groups I then see the toggle and it's already 'on'

Device: iPhone 6, iPhone 7, iPad
OS: 10.3.3, 11.2.2, 10.3.2
App version: build 135