[CHE 41] Create Registration Endpoints

[brok3turtl3]

Description

This ticket is part of CHE-23 Create User Registration story and modifies the existing registration route to work with the graduateInvitation data.

Jira Task

CHE-41

Testing Instructions

1. Run dev-ts script to spin up a local server for Postman testing.
2. Send a variety of requests to ensure that only a properly structured request sent with a valid token results in a new
   user.

Checklist

• I added a descriptive title to this PR.
• I filled out the Description, Jira Task, and Testing Instructions sections above.
• I added or updated [Jest unit tests]for any changes to components, server-side controllers, etc.
• I ran npm run docker-test in my local environment to check that this PR passes all unit tests.
• I did a quick check to make sure my code changes follow the recomended style guide.

Additional Notes, Images, etc.

N/A