Update iam workflow

[christopherm99]

Ideally, I think it makes more sense to first verify users' email, to check they are a student, and then subsequently detect which team they are on, as the server grows. For instance, manually adding and removing users as they join various public events such as DataFests.

Thus setting up a system like ACM's verification, then team assignment workflow may make more sense. To this end, we could also require members to declare their name when calling the /iam command. Then, after being verified as a student, users can react to a message to request to join various teams.

• /iam registers user nicknames (and users cannot modify their own names).
• /iam is broken out into two separate tasks, one to verify users, and the other to enroll in a team.
• MEE6 could be replaced for assigning users the DataLearn role.
• In the future, users could even request to join other teams (ie. after an internal transfer) and after being approved by the corresponding team head, the Google Sheet would auto update.

[christopherm99]

Closing this in favor of the solution in #16.