[PROJECT] Keep a single class to represent an Email

[leonardoaramaki]

Currently, on the SDK, we have two classes to represent an e-mail, which are:

• https://github.com/RocketChat/Rocket.Chat.Kotlin.SDK/blob/develop/core/src/main/kotlin/chat/rocket/core/model/Email.kt and
• https://github.com/RocketChat/Rocket.Chat.Kotlin.SDK/blob/develop/common/src/main/kotlin/chat/rocket/common/model/Email.kt

We should keep one.

[GOVINDDIXIT]

@leonardoaramaki I would like to work on this issue