[Dashboard] Add external-DWOC attribute to workspaces

[AObuchow]

Is your task related to a problem? Please describe

For #21405, it is required that workspaces use the Che-Operator created DWOC so that they can respect the PVC configuration settings set in the Eclipse Che CR.

Describe the solution you'd like

The attribute controller.devfile.io/devworkspace-config needs to be injected by the dashboard into devfiles (or devworkspaces) when a user starts a workspace. The attribute has two values: name which needs to be set to devworkspace-config and namespace which should be set to the namespace that che is deployed to.
For example:

 attributes:
+  controller.devfile.io/devworkspace-config:
+    name: devworkspace-config
+    namespace: eclipse-che

Describe alternatives you've considered

No response

Additional context

No response