Popup Notification for Session Request

[nzeager]

Is your feature request related to a problem? Please describe.
As a mentor it's better to know sooner rather than later when someone has set up a session. It can also be tedious to have to log into the app and confirm a session every time you get a request.

Describe the solution you'd like
We could add a popup notification if a mentor is already on the site that a session has been requested. This makes it more likely to catch there attention and gives them a chance to confirm/cancel before they log out.

Describe alternatives you've considered
It could also be useful to add popup notifications for session confirmation/cancellation. Those don't require a timely response, but could still be useful.