If we need to remove PVC and PV when delete MongoDB operator

[horis233]

@kgcarr
If we need to remove PVC and PV when deleting MongoDB.

If we don't need to we can remove the function addControlleronPVC
https://github.com/IBM/ibm-mongodb-operator/blob/master/pkg/controller/mongodb/mongodb_controller.go#L315

[horis233]

Common services operators don’t need to specify spec.customresourcedefinitions.required in their CSV.

In the Q1 release, there is no dependency management from ODLM, all the required operators need to be added into OperandRequest instance.

In the Q2 release, operators will use OperandRequest to manage their own dependencies.

[kgcarr]

To protect the customer, I don't think we should have the operator delete the PV. If we uninstall and re-install to fix a problem, their data should still exist. When the customer knows they will not want the data anymore they will have to delete manually. @horis233