Adjusts all cases of the room preview bar to mention the room name explicitly
when possible.

Use more specifc text for when previewing an invite to a direct message room.

This removes the clickable inviter behaviour, as it was too confusing to reveal
the user info sidebar and also hide the invite. Keeping both on screen would be
okay, but seems a bit too complex to resolve right before RC.

In addition, this adds the full inviter MXID to ensure it's clear who invited
you.

This changes to the room avatar instead of the inviter's avatar.