Allow specify workspace pods schedulerName via CheCluster spec

[ibuziuk]

Is your task related to a problem? Please describe

There are some specialized Kubernetes scheduler that can improve workspaces performances. One example is Portworx Stork. To use those schedulers pod should reference them in the PodSpec.schedulerName field.

Describe the solution you'd like

Now it is possible to set arbitrary fields of the workspace Pod and containers and we need a dedicated CR property in Eclipse Che operator for setting the schedulerName:

spec.DevEnvironments.defaultPodSchedularName

under the hood, Che operator would propagate this value to the managed DWOC, and set correct value for schedulerName e.g. config.workspace.podSecurityContext.schedulerName:

Describe alternatives you've considered

Release Notes Text

Before, the Kubernetes scheduler that managed Che workspaces was always the default one. Now Che administrators can specify an alternative Kubernetes scheduler using the CheCluster custom resource.

[dkwon17]

Hi @ibuziuk , I made a PR on the DWO side: devfile/devworkspace-operator#976, but instead of config.workspace.podSecurityContext.schedulerName, the PR introduces config.workspace.schedulerName, because schedulerName is not part of a pod's podSecurityContext (DWOC types, corev1 types), WDYT?

[dkwon17]

Fixed thanks to eclipse-che/che-operator#1587

The schedulerName for workspace pods is now configured within spec.devEnvironments.podSchedulerName in the Che CR