Standarization of scaladoc settings

Scala3 requires documentation tool. As we were in a little hurry, we created MVP that conforms 99% of what daily user needs. Since we finally have some time to enhance and polish the tool, we wanted to reach feature parity with Scala2 scaladoc so migration won’t be any trouble.

The current status of that issue can be tracked here

Most of the flags are already implemented. The ones we decided to drop are implicit and diagram flags family, since diagram creation and gathering data about implicits/givens is not a problem, though we are eager to hear your opinion about it.

On the other hand we were considering in updating Scala2 doc with features like project-logo, revision or social-links in a footer. Also, we could reimplement source links (revision aware) and external doc links (apparently not working in Scala2?)

Let me know what you think about that directly here in this thread or in github issue thread.