[BACKEND] Add user role management functionality to auth service

[choden-dev]

Is your feature request related to a problem? Please describe.

The Auth service will be involved in creating and promoting users. Users should NOT provide a password on signup, rather get sent a reset email.

Describe the solution you'd like
Take a look at:

• deleting a user
• creating a user with email address
  also allow it to add/remove claims on a user
• custom claims allow adding and removing claims

BEFORE MERGING

• Integration test written for services
• Code generation run (hint: yarn workspace server tsoa spec-and-routes)
• Appropriate mocks created where possible
• PR Reviewed (For non-trivial changes)
• Changes tested after rebasing on master or merging in master (hint: git fetch origin master:master, then git rebase master or git merge master)
• All required PR checks passing