JENA-2339: Dynamic graph restriction extension

[vtermanis]

Jira issue: https://issues.apache.org/jira/browse/JENA-2339

Pull request Description:

Extend jena-fuseki-access to support dynamic graph visibility choice at query time. The details of the what/why/how I've put in a separate document (simply due to the amount of information).

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• [x] Tests are included.
• [ ] Documentation change and updates are provided for the Apache Jena website
  • Not yet - would like to hear whether the extension is likely to be accepted in some form
• [x] Commits have been squashed to remove intermediate development commit messages.
• [x] Key commit messages start with the issue number (GH-xxxx or JENA-xxxx)
  • I've left a separate "to remove" commit with just a markdown page detailing the what/why/how which can be removed later.

By submitting this pull request, I acknowledge that I am making a contribution to the Apache Software Foundation under the terms and conditions of the Contributor's Agreement.

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See the Apache Jena "Contributing" guide.

Edit: Please note: I'm on leave until 24/07 so I won't be able to respond to feedback/questions until then.

[afs]

Discussion is on the Jena dev@ mailing list.

[afs]

See discussion : https://lists.apache.org/thread/dgnhbtf4p3sdnrwzxpml5yo1mr9cjh43

There is another way to achieve the necessary goals.

Closing this PR (which will still be here) for now.