astbuilder: Add a `create_callsite` method
astbuilder: Add a `create_callsite` method

Add a `create_callsite` method to facilitate the construction of callsite.

Signed-off-by: Florian Deljarry <947961b90cb93a9343e8ca0457b9d463c3e20c1c@gmail.com>

privat/nit,privat/nit,privat/nit,privat/nit,privat/nit,privat/nit,privat/nit,privat/nit,privat/nit,privat/nit