Add Kubernetes 1.16

[tjkirch]

This adds a Kubernetes 1.16 package and a new aws-k8s-1.16 variant that uses it.

Notes for reviewers:

• It would probably help to review the commits in order rather than the full diff.
• The contents of packages/kubernetes-1.16 are identical to 1.15 save for:
  • the version number
  • the removal of patch 0005 that's no longer needed to build
  • the clarify.toml changes mentioned in the commit message - don't be scared by all the green files, they're just copies
  • the patch updating aws-sdk-go for IMDSv2 support

commit 3951d35795b3b9bda04b040fb0b4a088772453ac
Author: Tom Kirchner <tjk@amazon.com>
Date:   Wed Apr 29 16:38:08 2020 -0700

Allow overriding package name in packages/*/Cargo.toml

Cargo doesn't allow some common characters like "." in a package name, which
would normally prevent you from naming package artifacts with those characters.
With this change, if you specify `package.metadata.build-package.package-name`
in Cargo.toml, you can override the package name and tell the build system to
look at your preferred name for the package directory, spec file, etc.

commit 3c37c20ebbbf138d31d157fbee07e42d18a7a6a1
Author: Tom Kirchner <tjk@amazon.com>
Date:   Wed Apr 29 16:41:26 2020 -0700

Rename Kubernetes package to 1.15 to make way for new versions

The main change is adding a version to the name of the kubelet package so that
the variant can pick the relevant Kubernetes version.

commit b33daa132027c9ab67bac59256935676cbbb0ef0
Author: Tom Kirchner <tjk@amazon.com>
Date:   Wed Apr 29 16:43:28 2020 -0700

Add Kubernetes 1.16

There are only minor changes from 1.15 packaging:
* We no longer need the patch related to go module building.
* The source of the go-bindata dependency changed, so clarify.toml is updated.
* The new go-tools dependency needed a clarify.toml entry.

commit 851d2368ff7eaf603d68e01b6ac16e68ae70ca51
Author: Tom Kirchner <tjk@amazon.com>
Date:   Wed Apr 29 16:45:24 2020 -0700

Add aws-k8s-1.16 variant

No model changes are required from aws-k8s-1.15, so the model is a symlink.
The only differences from aws-k8s-1.15 are the name and the kubelet version.

commit b60a8daaef266d9183721e137c6b4e0453ab8e63
Author: Tom Kirchner <tjk@amazon.com>
Date:   Wed May 6 16:51:09 2020 -0700

Add patch updating k8s 1.16's aws-sdk-go for IMDSv2 support

Testing done:

Built an aws-k8s-1.15 AMI, still works fine.

Built an aws-k8s-1.16 AMI, it joins my cluster and shows the new version:

$ kubectl get nodes
NAME                                          STATUS   ROLES    AGE     VERSION
ip-192-168-15-23.us-west-2.compute.internal   Ready    <none>   4m40s   v1.16.9

A pod runs fine. System services running. API settings look OK.

I diffed the kubelet service log between 1.15 and 1.16 and found no substantive changes, just minor bits: a number of lines were reordered, some source filenames changed, some old debug lines were removed, there's a new "fake_topology_manager", and a new (presumably related) ExperimentalTopologyManagerPolicy:none in the node config (which becomes not-experimental in a later k8s release).

The 1.16 AMI passes Sonobuoy testing with conformance version 1.16.8 (matching EKS) in a 1.16 cluster:

Plugin: e2e
Status: passed
Total: 4731
Passed: 276
Failed: 0
Skipped: 4455

Terms of contribution:

By submitting this pull request, I agree that this contribution is dual-licensed under the terms of both the Apache License, version 2.0, and the MIT license.

[tjkirch]

This push addresses @bcressey's concern, and adds a commit with a patch updating aws-sdk-go for IMDSv2 support. I also updated the Testing Done to show sonobuoy conformance.

[tjkirch]

I added a commit that updates documentation to reference the new aws-k8s-1.16 variant. I was going to put it in a separate PR, but because this won't be our default variant yet, the updates were minimal and I figured it was simpler to include it here.

[tjkirch]

This push simplifies the documentation update, per discussion with @bcressey.

[zmrow]

🍶