pkg/errors is archived and while there is go-errors/errors as
an alternative, it lacks wraping methods. kubeadm has
specific neends and it's better to implement something
minimal locally instead of introducing another depedency.
- Implement basic wrapped errors and stack trace support.
cmd/kubeadm/app/util/errors.
- Remove unused error codes >1. At some point it seems we broke
these and 1 was returned for all error types.
- Remove the Error type in preflight and separate the printing
of '[preflight]' message and the error return from preflight
checks.
- Print an 'error:' prefix for all errors.
