Remove deprecated methods from ast package

[abelsromero]

Methods already marked should be removed for v3.0.0 release.

This includes mostly methods whose naming was aligned with Ruby and have now equivalent Java versions (same as #1202 (comment)).

We'll need to document these changes in the migration guide.

[abelsromero]

Finally, this is the last thing I have in mind for v3.0.0 release. @robertpanzer anything else?

[robertpanzer]

Sorry for responding late.
I don't have anything on the top of my mind.
Do you think it would make sense to release sth like a 3.0.0-alpha.1?

[abelsromero]

Do you think it would make sense to release sth like a 3.0.0-alpha.1?

I guess I have been too subtle 🙊 Let's release!

For transparency, I am really looking forward to v3.0.0 because we also have the maven-plugin v3.0.0 ready with heavy breaking changes, and I'd like to make Asciidocotorj v3 the minimum for it. It could be made optional, but is less cognitive overload, and in case of need, we also have a maven v2.5.x maintenance for older versions.