Include ability to register for courses through GraphQL mutations

**Is your feature request related to a problem? Please describe.**
This API is being built to allow access to as much student portal information as possible but I have to visit my portal to actually perform any actions or make changes. I would like to be able to perform actions through webadvisor-api.

**Describe the solution you'd like**
Include actions / changes via GraphQL mutations upon already present or future data. This will require authentication to be handled in a secure manner.

**Additional context**
In the discussion of this issue, I would like to determine if any such methods exist to provide secure and trustworthy methods of authentication. This is of utmost importance of determining whether any actions are viable.