Replace boilerplate code with Lombok

[rufus20145]

If you don`t mind, I`ll rewrite model classes with Lombok for easier updates in future and to avoid such a mess like in BotCommand

[anfanik]

New classes in the library are written in Kotlin, so we don’t need to use Lombok to clean up the code.

[rufus20145]

I really liked Lombok-style accessors that omit the get/set prefixes. In my opinion, they're much more readable, especially when used in method chaining. From what I can tell, Kotlin generates accessors with get/set, which is a bit disappointing. 😢

That said, I can still start rewriting the old classes in Kotlin.