We always use the same directory for terraform fixtures, so it's quite
easy to figure out its path from a pytest fixture by inspecting the
stack. This commit implements this functionality and decreases the
amount of boilerplate needed to write a test.
(Ported from fast)
* group_iam support for organization
* group_iam support for folder
* fix typo in variable description
* add group_iam to project module
* update project module README