Add behaviors to AST Visitors

[Kuinox]

We should add an enum to have the AST Visitor adopt a certain behavior.
For example, currently the AST Visitor Visit the most specific node and that it, we may want that the Visitor call the base Visitor (which is very practical in the code Formatter), this should be optional since it come at a performance cost.

[Kuinox]

The formatter PR will add the described behavior but it won't be optional. The purpose of this issue/pr is to make it optional.