Improve replies

[SimonBrandner]

There are a few things that could be improved in replies:

• The copy is a bit weird when replying to oneself (In reply to <my name>) - we can use Expand replies
• The In reply to <someone> copy is super confusing - we can use Expand replies
• Reply threads look confusing - change the copy as mentioned above and add a hover effect to Expand replies
• New-style reply design can be harder to grok - make the messages being replied to a bit light/grayer
• We should indicate replied-to messages are clickable in new reply UI - add a hover effect
• Replies don't have an avatar - add a small avatar
• The Edited sign doesn't seem to be necessary in replies - we can remove it