Support HA mode with embedded DB

This enables initializing a cluster in HA mode with an embedded DB.
https://rancher.com/docs/k3s/latest/en/installation/ha-embedded/



When multiple masters are specified in the master group, k3s-ansible will add
the necessary flags during the initialization phase.
(i.e. --cluster-init and --server)

For the embedded HA mode to work the k3s version must be >= v1.19.1

Signed-off-by: Julien DOCHE <julien.doche@gmail.com>