Email Clean Architecture + Tests

[lucieyang1]

Description

Refactored email usecase to use clean architecture and wrote tests. Tests have 100% coverage of the email use case :)
Refactoring it into ca made it weird to handle errors and give the NOT_FOUND http response entity, so I made some custom exceptions?

Type of change

• [X]

How Has This Been Tested?

• EmailTests.java
• Also manually tested, still works as before!

Checklist:

• My code follows the style guidelines of this project
• I have performed a self-review of my code
• I have commented my code, particularly in hard-to-understand areas
• My changes generate no new warnings
• I have added tests that prove my fix is effective or that my feature works
• New and existing unit tests pass locally with my changes

[sarinali]

LGTM, add a screenshot of test coverage please