Merge: astbuilder: First implementation of clonable for ast nodes

## Astbuilder

- Now all the nodes of the ast is cloneable. Currently just a part of node have an implemented clone method.If we clone a node by default (not implemented) the program abort and print the following message: `The clone method is not implemented for ATestNode class.`. Currently the library is in **test** phase. You can have "maybe" some bug with the clone.

- Add a method to make the creation of a callsite easier.

## Futur work

Currently i am working on a test to make sure the result clone is the same as the original.

Pull-Request: #2779
Reviewed-by: Jean Privat <jean@pryen.org>

diff --cc tests/niti.skip
Simple merge

diff --cc tests/nitvm.skip
Simple merge