feat(chart): option to not create clusterRoles;

[mariuskimmina]

Related to #170 and #162

When destroying and re-creating the operator (for example when moving to another namespace) we want to keep CRDs and ClusterRoles around. This PR adds an option createClusterRoles to the helm chart which can be used to re-create the operator without re-creating the ClusterRoles, which would currently fail. The default value is true and thus default behavior of the chart will not change.

This PR has:

• [x] been tested on a real K8S cluster to ensure creation of a brand new Druid cluster works.

[mariuskimmina]

Any thoughts @AdheipSingh ?

[mariuskimmina]

Hey @AdheipSingh we'd really love to see a new release with this and #162 (already merged) included. Let me know if you have any concerns.