Create GitLab CR install functional test

Followup to #43 (closed), which involved creating a test to verify that the operator itself installs without error.

We now need a test that installs the GitLab CR (CustomResource) that the operator manages and ensures that GitLab starts correctly. This test should be simple, just checking GitLab is running.

We will create a followup to this issue to start running gitlab-qa against the operator-installed GitLab.

Edited by Dustin Collins