[CHE-199] Create Tests and Error Handling for userController registerUser

[seantokuzo]

Description

As part of the CHE-73/BE-Controller-Files story, this PR aims to:

• Abstract out registerUser middleware into it's own file (in new server/controllers/userController/ directory)
• Refactor registerUser to make use of new error handling
• Add test coverage for registerUser

Other things included with the changes above:

• Create reusable utility functions for validating email and password inputs
• Create a reusable utility function for attaching auth cookies to responses
• Simplify imports of utilities
• update registerUser import in userRouter
• Remove unused registerUser middleware from userController.ts
• Remove registerUser tests that have been replaced

Jira Task

JIRA TICKET

Testing Instructions

• run npm run docker-test:solo register to run new unit tests on registerUser middleware
• manual review of server/controllers/userController/registerUser/registerUser.test.ts to make sure all possible request cases are covered

Checklist

All Team Members

• 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-build-check in my local environment to check that this PR passes all linting and unit tests.
• I did a quick check to make sure my code changes follow the recommended style guide.

[brok3turtl3]

@seantokuzo Great job on your first refactor and test ticket. 🎉

👍 I like the utility separation as well.

🛑 Left a couple comments and one request to delete the tests file. I think you can probably just go ahead and delete all the test files in that folder. Most of them wouldn't be recognizable after the reactors anyway.

[brok3turtl3]

@seantokuzo If we end up using this in the login flow as well, we will have to figure out how to deal with existing users that have passwords that don't meet this criteria.

[seantokuzo]

I don't think we'll need to use it for login, just enforcing stronger passwords when created. It's kind of overkill to abstract it out with just the 'password.length > 7' check, but good if we decide to enforce more conditions

[brok3turtl3]

@seantokuzo Great work 🎉