refactor: use newtype pattern for email addresses

[nachiketkanore]

Type of Change

• [ ] Bugfix
• [x] New feature
• [x] Enhancement
• [ ] Refactoring
• [ ] Dependency updates

Description

• This fixes #608
• Added testcases

Additional Changes

• [ ] This PR modifies the database schema
• [ ] This PR modifies application configuration/environment variables

Motivation and Context

#608

How did you test it?

• ran cargo test
• Added 2 unit testcases for validation of implemented code
• 

Checklist

• [x] I formatted the code cargo +nightly fmt --all
• [x] I addressed lints thrown by cargo clippy
• [x] I reviewed submitted code
• [x] I added unit tests for my changes where possible
• [x] I added a CHANGELOG entry if applicable

[nachiketkanore]

• Shouldn't std::fmt::Debug be implemented for struct Email(Secret<String>)? Since, we will be calling format!(email) where email: Email(Secret<String>)
• So, Email(Secret<String>) will replace both Email(String) and Secret<String, Email>? @SanchithHegde

[SanchithHegde]

• Shouldn't std::fmt::Debug be implemented for struct Email(Secret)? Since, we will be calling format!(email) where email: Email(Secret)

You should be able to derive Debug on Email(Secret<String>) since Secret implements Debug already.

• So, Email(Secret) will replace both Email(String) and Secret<String, Email>?

I'm not sure if there are any types of the form Email(String) in our code. But if there are any, please do replace that and Secret<String, Email> with Email(Secret<String>).

[nachiketkanore]

let secret: Secret<String, Email> = Secret::new("[email protected]".to_string());
assert_eq!("*******@gmail.com", format!("{secret:?}"));

What about these tests?

[SanchithHegde]

You'd have to update/remove tests accordingly.

[nachiketkanore]

Sorry, this got closed by mistake. I was trying to sync with the remote, but somehow the PR closed.

[nachiketkanore]

Done

[nachiketkanore]

Done Made suggested changes