* Make sure include_role inherit variables from parent role
Setting the parent of task blocks generated by include_role after they
have been produced is not sufficient - it means the tasks don't have the
correct dependency chain set afterwards, and therefore, don't properly
inherit variables from outer roles.
In addition to manually setting the parents, pass the dep_chain when
compiling the role, such that variables are correctly imported.
Fixes#18540.
* Add tests for include_role
* Fix include_role variable inheritance for multiple parent levels
