[server] use owner and repo name for workspace id

[svenefftinge]

This change introduces optional arguments in generateWorkspaceId
for the first two segments. And makes use of it in workspace factory
using the repos org/group and name.

fixes #4129

Testing

Start a workspace on GitHub and GitLab repos (try with nested groups on GitLab) and find the repo names and orgs reflected in the workspace id.

Release Notes

Use repository org and name for workspace ids.

[roboquat]

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Associated issue: #4129

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[svenefftinge]

Closing because the branch name is too long to get deployed 🙄