Add extends redeclare update method

[nllong]

Handle a very specific case where we need to set an argument that is part of an extended block.

extends extended_type(
    redeclare type_ identifier[X](final Y=Y),
    obj_name(
        arg_1=8,
        arg_2=1029.114,
        arg_name=new_value (if_value)
    )
);

[nllong]

@jmythms -- do you want to check this one out too?

[jmythms]

@jmythms -- do you want to check this one out too?

Will be a bit late but definitely :)