DevWorkspace operator should not ignore SA dockercon if additional pullSecret is configured

[sleshchenko]

Issue is well described in https://issues.redhat.com/browse/CRW-1925
The main idea - after users configures pull secret, they are not able to use internal registry without adding explicitly SA token into that pull secret.

I suppose it's not handled in DWO as well, so DWO should mount additional pull secret in addition to workspace SA dockerconf but not instead.

[sparkoo]

Issue is that when we don't define imagePullSecret for the workspace deployment, OpenShift adds default one for the service account. That's why OpenShift registry works at first. Once we define custom user imagePullSecret, OpenShift does not add it's default one, thus we cannot authenticate against openshift registry anymore.

The code responsible for provisioning image pull secrets lives here https://github.com/eclipse-che/che-server/blob/main/infrastructures/kubernetes/src/main/java/org/eclipse/che/workspace/infrastructure/kubernetes/provision/ImagePullSecretProvisioner.java#L66 and combined into deployment here https://github.com/eclipse-che/che-server/blob/main/infrastructures/kubernetes/src/main/java/org/eclipse/che/workspace/infrastructure/kubernetes/environment/PodMerger.java#L74. It is possible to define multiple pull secrets for the deployment, so I think we should be able to always include the che-workspace SA dockerfcg secret in the deployment.

[sleshchenko]

fixed by #566