Add destination kubeconfig option

[christianh814]

In the case where Argo CD is installed on another cluster, there's no way to specify that destination cluster. It would be nice to add a global flag --destination-kubeconfig for the end user to provide that destination cluster's Kubeconfig.

Example:

mta scan --auto-migrate --confirm --destination-kubeconfig /path/to/argocd/kube.config

Current workaround is to migrate components using kubectl

Example:

mta helmrelease --name sample | kubectl apply --kubeconfig  /path/to/argocd/kube.config -f -