Check if time is synced between Kubernetes cluster and GitLab

Problem to solve

In support we faced several cases (at least 3 that I know of) when GitLab managed apps were failing to install because the time between Kubernetes cluster and GitLab was not in sync. A note about it was added to Installing applications.

Proposal

I suppose we can improve it and add some check to application to make sure that the time is in sync between GitLab instance and kubernetes cluster.

Links / references

https://docs.gitlab.com/ee/user/project/clusters/#installing-applications

/cc @DylanGriffith