#167733813 Set up sign-in endpoint

[Ileriayo]

What does this PR do?

• It sets up the endpoint to allow a user log into the app

Description of Task to be completed?

• Write unit tests for the login endpoint
• Write login controller logic to pass the test cases
• Ensure that test coverage does not drop
• Document the endpoint using Swagger

How should this be manually tested?

• On Postman send a POST request to /api/v1/auth/signin with email and password as parameters

Any background context you want to provide?

• N/A

What are the relevant pivotal tracker stories?

• #167733813

Screenshots (if appropriate)

[fegzycole]

This is good to go

[tamunoibi]

Looks good. Great job.

[fegzycole]

Good Job