179 refactor application applicant

[anjalisilina]

ℹ️ Issue

Closes #179

📝 Description

Briefly list the changes made to the code:

1. Moved startDate and endDate fields to Application from Applicant and refactored corresponding tests, endpoints and Application files
2. Changed Applicant to CandidateInfo and refactored files
3. Changed Admin to AdminInfo and refactored files
4. Made email the primary key for both CandidateInfo and AdminInfo
5. Deleted firstName and lastName fields for both CandidateInfo and AdminInfo

✔️ Verification

Ran and passed updated tests:

New directories:

🏕️ (Optional) Future Work / Notes

Might be other places to refactor these changes including migrations

[SamNie2027]

The actual endpoints and data structure are still called applicant - can you fix that to be candidate? Otherwise looks good, although there are merge conflicts to resolve as well.