conference: improve participant overlay

- In another participant video, if I am moderator, I will see local state at bottom and moderator state on top;
- In another participant video, if I am NOT moderator, I will see only one state at bottom representing both local and moderator;
- In my own video, if I am NOT moderator, I will have my local state at bottom left and moderator state top left with a tooltip but no action;
- In my own video, if I am moderator, I will have my local state at bottom left and moderator state top left with an action.

Change-Id: I649d4aeefdd15aa3b554d78948849804ad94a9cd
GitLab: #593