What does this PR do?

• This PR addresses requested feedback and implements the necessary changes to improve the application's functionality and user experience.

Description of the task to be completed

• Removed the 'submitted' status to streamline application tracking.
• Enabled adding comments for applications marked with the 'rejected' status, providing clarity on rejection reasons.

How can this be manually tested?

• Clone repo
• Checkout branch fix-applicant-process
• Make sure that you set the environment variables referring to .env.example
• Run npm install, then npm run dev to check if the app is running successfully
• login as admin with username: [email protected] and password: password123
• Applying to a job post using the createNewJobApplication mutation. The status returned should be 'under review', and not 'submitted'
• • login as admin with username: [email protected] and password: password123
• Reject job application and add comments when rejecting an applicant, through the changeApplicationStatus mutation