Chat should permanently indicate whether message expiration is set up

[nickvergessen]

There are cases which can lead to a completely empty chat and also it could be burried in a history or something.

• Ref If all messages expire, the chat shows the loading animation #7919
  Any idea about the visual design? cc @nimishavijay @marcoambrosini @jancborchardt

• Topbar?

• Chat input?

• Right sidebar?

• Burried in conversation settings?

• Floating on enter? (Not too accessible?)

[marcoambrosini]

I would put it both in the messages list and in the input field