Mentor Option to Limit How Soon Mentees Can Schedule Sessions

[nzeager]

Is your feature request related to a problem? Please describe.
Mentees sometimes schedule sessions just a few minutes ahead of time, not giving mentors much time to prepare (or even notice it has been scheduled). Some mentors feel they have to put other plans on hold when setting availability, not knowing if anyone will sign up.

Describe the solution you'd like
We could give mentees an option in their profile for how much notice they'd like to have. Something like "Mentees must sign up for sessions at least _ hours ahead of time."

Describe alternatives you've considered
Mentors can currently write out their preferences in their About Me, and that will display when mentees are on the Session Signup page, but they don't always pay attention to that.

[esparr]

@nzeager I think this is a duplicate issue with https://github.com/orgs/TeamProductionSystem/projects/2/views/1?pane=issue&itemId=44515348

Mind confirming before I close this one?