Add the ability to disable mobile icon without being invisible

Per the support article the only way to disable mobile presence is to turn on invisibility.
A better option would be to add the ability to just turn off mobile presence and remain visible.

This would benefit users who are both on PC and mobile but perhaps had to step away to the restroom, so they're still active but just not at the PC and other users won't think they're just not there or shirking responsibilities. There are a lot of other reasons this could be wanted as well