DevWorkspace must not be created if default plugins fails to load

[sleshchenko]

Describe the bug

DevWorkspace must not be created if default plugins fails to load.
Currently, when dashboard fails to load plugins, it creates DevWorkspace without any DevWorkspaceTemplates, which means - no Theia is injected.
Dashboard must not create DevWorkspace without default plugins being injected, since it does not make sense since it will lead to can not evaluate workspace main URL since theia is missing.

Che version

• latest
• nightly
• other: please specify

Steps to reproduce

1. Configure https://che-plugin-registry-main.surge.sh/v3 to be used as external plugin registry.
2. Dashboard is going to fail to load that since it has CORS restrictions.
3. Try to create DevWorkspace.

Actual behavior: DevWorkspace is created but failed to open.

Expected behavior

Users to told that plugin registry does not have configured default plugins.

Runtime

• kubernetes (include output of kubectl version)
• Openshift (include output of oc version)
• minikube (include output of minikube version and kubectl version)
• minishift (include output of minishift version and oc version)
• docker-desktop + K8S (include output of docker version and kubectl version)
• other: (please specify)

Screenshots

Installation method

• chectl
  • provide a full command that was used to deploy Eclipse Che (including the output)
  • provide an output of chectl version command
• OperatorHub
• I don't know

Environment

• my computer
  • Windows
  • Linux
  • macOS
• Cloud
  • Amazon
  • Azure
  • GCE
  • other (please specify)
• Dev Sandbox (workspaces.openshift.com)
• other: please specify

Eclipse Che Logs

Additional context