- Rename FindExistingKubeConfig to GetKubeConfigPath
- Cobra supports a DefValue option which can be used
to differentiate between the cases where the user set a flag
and when a flag was unset, while still adding a default value.
Use this in options/generic.go for the kubeconfig flag.
- Remove the GetKubeConfigPath() logic from `reset` and `upgrade`
as these are node level kubeadm commands.
- Default kubeconfig values to "" everywhere where GetKubeConfigPath
is used. This allows to search for existing kubeconfig locations.