Add a workspace storage volume mount for che-theia editor

[vinokurig]

What does this PR do?

Add a workspace storage volume mount for che-theia editor. The GitHub authentication session is saved in this directory, so the GitHub authentication will be restored after workspace restart.

Screenshot/screencast of this PR

What issues does this PR fix or reference?

fixes eclipse-che/che#18664

How to test this PR?

Open the che-theia's editor meta.yaml (< plugin registry url >/v3/plugins/eclipse/che-theia/next/) and see the workspace storage volume mount:

      volumes:
        - name: plugins
          mountPath: /plugins
        - name: workspaceStorage
          mountPath: /home/theia/.theia/workspace-storage

PR Checklist

As the author of this Pull Request I made sure that:

• The Eclipse Contributor Agreement is valid
• Code produced is complete
• Code builds without errors
• Tests are covering the bugfix
• The repository devfile is up to date and works
• Sections What issues does this PR fix or reference and How to test this PR completed
• Relevant user documentation updated
• Relevant contributing documentation updated
• CI/CD changes implemented, documented and communicated

Reviewers

Reviewers, please comment how you tested the PR when approving it.

[ericwill]

Forgot to approve last week, LGTM

[sunix]

@vinokurig so the referenced issue is not the right one in description

[vinokurig]

@sunix, yes, I reopened the mistakenly closed issue and closed the right one.