Adds Crossplane as CI/CD Managed App

Relates to gitlab-org/gitlab#35675 (closed)

Manual QA

Disclaimer

While introducing this change we found out that the current version of Crossplane is broken live. (2020-03-11)

It has a sub-component which is pinned to a floating version. This version isn't anymore compatible with the current chart version (0.4.1). See gitlab-org/gitlab!27040 (merged) for more details.

So, this MR will already contain the fix for it. Although, we also believe that the 0.4.1 was also dependent on whatever was present in this floating version at the point when it was integrated. So simply removing the pin, does not completely fix Crossplane integration. Disscussion about this is being pushed forward, see:

gitlab-org/gitlab!27040 (comment 304089569)

gitlab-org/gitlab!27040 (comment 304081778)

That being said, this MR will aim to keep Crossplane CI/CD as close to one-click as possible.

QA

After installing crossplane: