Support Heal operation for CNF

The heal operation is defined in ETSI NFV-SOL 003 and 002 as a part of VNF
Lifecycle Management Interface. In NFV-SOL003 v2.6.1 [1], NFVO asks VNFM to
heal a VNF instance, while, in NFV-SOL 002 2.6.1 [2], VNF/EM can also request
VNFM to heal a VNFC in the VNF instance.

In this spec, the heal operation for a VNF with OS containers is proposed. The
heal operation of a VNF instance provides termination and instantiation of the
VNF. For the heal operation of VNFC, a controller resource in Kubernetes such
as Deployment, DaemonSet, StatefulSet, or ReplicaSet is defined as VNFC, and
it enables to respawn the VNFC instance.

[1] https://www.etsi.org/deliver/etsi_gs/NFV-SOL/001_099/003/02.06.01_60/gs_NFV-SOL003v020601p.pdf
[2] https://www.etsi.org/deliver/etsi_gs/NFV-SOL/001_099/002/02.06.01_60/gs_NFV-SOL002v020601p.pdf