Provide initContainers field in the CheCluster CR

[dkwon17]

Is your enhancement related to a problem? Please describe

DWO version 0.39.0 provides a feature for configuring initcontainers for DevWorkspaces from the DWOC:

apiVersion: controller.devfile.io/v1alpha1
kind: DevWorkspaceOperatorConfig
metadata:
  name: devworkspace-operator-config
  namespace: $OPERATOR_NAMESPACE
config:
  workspace:
    initContainers:
      ...

Describe the solution you'd like

This issue tracks the task to introduce this field in the CheCluster field too, for example:

apiVersion: org.eclipse.che/v2
kind: CheCluster
metadata:
  name: che
  namespace: eclipse-che
spec:
  devEnvironments:
    initContainers: ...

Describe alternatives you've considered

No response

Additional context

No response