* add id to outputs
* initial cloud build implementation for stage 0
* comments
* stage 0
* stage 1, untested
* add support for IAM and CB triggers to source repository module
* refactor stage 0 to use sourcerepo module
* refactor stage 1 to use sourcerepo module
* file descriptions
* fix gitlab pipeline
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)