* Detect and prevent configuration that triggers a Gradle bug
As we found in #31862, this can lead to a lot of wasted time as it's not
immediatly obvius what's going on.
Givent how many projects we have it's getting increasingly easier to run
into gradle/gradle#847.
Similarly to what has been done in for the repository-s3 plugin,
this commit moves the fixture test into a dedicated
repository-gcs/qa/google-cloud-storage project.
It also exposes some environment variables which allows to
execute the integration tests against the real Google Cloud
Storage service. When the environment variables are not
defined, the integration tests are executed using the fixture
added in #28788. Related to #29349.
Alpar Torok
Tanguy Leroux