Appointment Backend

[DylanTom]

We are moving forward without Cal.com and integrating all the calendar features into the firebase and handling everything internally. As such we will need functions that determine whether a valid appointment has been made, setting up an appointment, etc.

Create a file in the backend folder called appointments.ts

For now as we build our suite of functions, please document each of the following ones (work with the IAppointment schema:

• Validating an appointment (with time) - this should verify that an appointment being made is in the future and not retroactively
• Overlapping appointments - this should return whether or not two appointments are overlaping with each other.
• Validating an appointment (with psychiatrist schedule) - should take in professional's appointment availability and a new appointment, return true if this matches and fits in their schedule

More functions will be added here as needed and if you find any functions that you deem necessary, add it here.