[CHE-40] Create User Registration

[brok3turtl3]

Description

This ticket is part of CHE-23 Create User Registration story and adds the graduateInvitation model as well as its type file. It also contains the work for CHE-43 adding a seeding script and dev routes for testing.

Jira Task

CHE-40

Testing Instructions

N/A

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