Support 3rd party tools which require kubeconfig

[stefanmcshane]

What does this PR do?

Support 3rd party tools which require a kubeconfig such as k9s.

• Added porter kubectl --print-kubeconfig flag which prints a generated kubeconfig to the console, with 15 minutes expiry.
• Added cobra.Command to all run functions, so we can start moving away from globally defined flags, allowing flag parsing within each individually run function

porter kubectl --print-kubeconfig | k9s --kubeconfig /dev/stdin would pipe the kubeconfig directly to k9s for example

[gitguardian]

️✅ There are no secrets present in this pull request anymore.

If these secrets were true positive and are still valid, we highly recommend you to revoke them.
Once a secret has been leaked into a git repository, you should consider it compromised, even if it was deleted immediately.
Find here more information about risks.

---

<sup><sub>🦉 GitGuardian detects secrets in your source code to help developers and security teams secure the modern development process. You are seeing this because you or someone else with access to this repository has authorized GitGuardian to scan your pull request.

Our GitHub checks need improvements? Share your feedbacks!</sub></sup>

[stefanmcshane]

Secret was a temporary certificate that was used during testing on a local cluster, and no longer exists. False positive