cmd/containerboot: manage HA Ingress TLS certs from containerboot
When ran as HA Ingress node, containerboot now can determine
whether it should manage TLS certs for the HA Ingress replicas
and call the LocalAPI cert endpoint to ensure initial issuance
and renewal of the shared TLS certs.
Updates tailscale/corp#24795
Signed-off-by: Irbe Krumina <irbe@tailscale.com>
