kubectl v1.13

Issue gitlab-org/gitlab#30495 (closed)

Includes !5 (merged) so that these get released at the same time. This image makes releases based on kubectl/helm versions. The only difference here is that I've modified kubectl to use an archive with a published sha for ease of updating.

Manually tested using gitlab MR gitlab-org/gitlab!18924 (merged)

Release notes for checksums:

• https://github.com/helm/helm/releases
• https://github.com/kubernetes/kubernetes/blob/master/CHANGELOG-1.13.md#client-binaries