Show presence inside 1:1 chat icon

[heylix]

Is your suggestion related to a problem? Please describe.

If I want to write with someone instead of calling them for an immediate response, I would like the user icon () to show information about their online status.

Describe the solution you'd like

The person icon could be filled with solid green if they're online, with yellow if they're online but haven't done anything in the last X minutes and white (as currently) if they're offline.

Describe alternatives you've considered

If you click on their 1:1 chat you can see in the user list of said chat when they were last online.

Additional context

This issue was raised by test123321__ in #riot-web:matrix.org.

[tulir]

Duplicate of #4199