Create helm charts for a clustered implementation of Cassandra.

Acceptance Criteria:

• data is persisted when db goes down via PVC/PV
• db nodes able to restart without losing stable data
• appropriate security
• image source is trusted
• table initialization appropriate for shared use
• logs integrated into ONAP logging
• automatic leader election
• able to dynamically add cluster members
• able to dynamically remove cluster members
• appropriate load balancing of external requests

Sub-tasks track migration of existing project implementations to these common charts.