Add `--insecure-skip-tls-verify` option

[dareste]

Is your feature request related to a problem? Please describe.
kubectl allows bypassing the certificate verification via the --insecure-skip-tls-verify flag. Customers willing to do so with the plugin nginx-supportpkg won't be able to.

Describe the solution you'd like
Make the --insecure-skip-tls-verify available to the plugin.