Support collecting client and helm versions

[markpundsack]

When troubleshooting some Kubernetes apps, it's useful to know things about the clients the user is using. Furthermore, since many people install via Helm, we should support various Helm information as well.

We should add the ability to collect:

1. kubectl client version
2. helm client version
3. helm server version
4. Helm chart version (implies ability to specify a Helm chart)
5. Helm values
6. helm repo list

This would help obviate tools like KubeSOS.

Note: client information wouldn't be accessible from embedded usage, such as in Kotsadm. I'm not sure if that's a problem, or if we should somehow make them optional, or a different type of spec completely so they're not accidentally included in Kotsadm. My first reaction is that it shouldn't be an error to include these kinds of specs in a Kotsadm definition, but to simply have Kotsadm carry on, perhaps with warnings. If combined with https://github.com/replicatedhq/troubleshoot/issues/231, this could allow a way for users to run most collectors from within the admin console, but also run them from the CLI, with some additional information.