[Feature] Add --insecure-skip-tls-verify when executing kubecm add

[mayooot]

In my use case, I need to skip the ca, so I need to set insecure-skip-tls-verify, like:

- cluster:
    server: https://ip-public:6443
    insecure-skip-tls-verify: true

However, kubecm add does not support this operation, so I changed the source code and it worked as expect.

An example is as follows:

$ kubecm add -f example.yaml --insecure-skip-tls-verify
$ kubecm add -h 
Add KubeConfig to $HOME/.kube/config

Usage:
  kubecm add [flags]
  kubecm add [command]

Aliases:
  add, a

Examples:

# Merge test.yaml with $HOME/.kube/config
kubecm add -f test.yaml 
# Merge test.yaml with $HOME/.kube/config and add a prefix before context name
kubecm add -cf test.yaml --context-prefix test
# Merge test.yaml with $HOME/.kube/config and define the attributes used for composing the context name
kubecm add -f test.yaml --context-template user,cluster
# Merge test.yaml with $HOME/.kube/config, define the attributes used for composing the context name and add a prefix before context name
kubecm add -f test.yaml --context-template user,cluster --context-prefix demo
# Merge test.yaml with $HOME/.kube/config and override context name, it's useful if there is only one context in the kubeconfig file
kubecm add -f test.yaml --context-name test
# Merge test.yaml with $HOME/.kube/config and select the context to be added in interactive mode
kubecm add -f test.yaml --select-context
# Merge test.yaml with $HOME/.kube/config and specify the context to be added
kubecm add -f test.yaml --context context1,context2
# Add kubeconfig from stdin
cat /etc/kubernetes/admin.conf | kubecm add -f -
# Merge test.yaml with $HOME/.kube/config and skip TLS certificate verification
kubecm add -f test.yaml --insecure-skip-tls-verify


Available Commands:
  docs        Open document website

Flags:
      --context strings            specify the context to be added
      --context-name string        override context name when add kubeconfig context, when context-name is set, context-prefix and context-template parameters will be ignored
      --context-prefix string      add a prefix before context name
      --context-template strings   define the attributes used for composing the context name, available values: filename, user, cluster, context, namespace (default [context])
  -c, --cover                      overwrite local kubeconfig files
  -f, --file string                path to merge kubeconfig files
  -h, --help                       help for add
      --insecure-skip-tls-verify   if true, the server's certificate will not be checked for validity
      --select-context             select the context to be added in interactive mode

Global Flags:
      --config string   path of kubeconfig (default "$HOME/.kube/config")
      --create          Create a new kubeconfig file if not exists
  -m, --mac-notify      enable to display Mac notification banner
  -s, --silence-table   enable/disable output of context table on successful config update (default true)
  -u, --ui-size int     number of list items to show in menu at once (default 7)

Use "kubecm add [command] --help" for more information about a command.

If you want to add this feature to kubecm, I will sumit a pr.

[sunny0826]

This is an absolutely amazing feature! Please feel free to submit a PR!

[mayooot]

ok, I'm done