Implements Container based VNF scale operation support with ETSI
NFV-SOL003 v2.6.1 VNF Lifecycle Management. Users can scale the number
of pod replicas managed by controller resources such as Kubernetes
Deployment, StatefulSet, and ReplicaSet.
Other changes:
* Check the vnf_state before scale operation in controller as other
LCM operations.
* Enable to store multiple flavour to `vnfd_attribute` when
`Conductor._onboard_vnfd()` method called.
* For FT, sqlalchemy is used, which calls functions in pymysql.py,
so the dependency module PyMySQL needs to be added.
Implements: blueprint support-cnf-scale
Spec: https://specs.openstack.org/openstack/tacker-specs/specs/wallaby/support-cnf-scale.rst
Change-Id: I739fa60a18323b248bc913f6062ef2138ad2e6ee
8a8948e616