Update database w preferred language, time-slot, email, tutorial type preference, whenever TA sheet from the main portal is updated

[msarvestani]

For DL, we need to update the full TA database in our portal whenever a new sheet is available. This is because TAs go through and update their preferred timeslots, language, and other parameters on the portal, so if we just add new applicants to our portal when we do database updates, it will reflect the old timeslots/languages and they'll be matched incorrectly.

This is specially important for DL, because we are going to triple remind people to confirm their preferred timeslots before we match them ( to prevent having to swap people after match which is super time consuming and error-prone). So the TA portal needs to have the latest updated timeslot preferences before we give the final list of enrolled TAs to Davide for matching.