Gh 2767 Fix Fuseki UI JavaScript warnings

[kinow]

GitHub issue resolved #2767

Pull request Description:

• Fixes grammar/typos
• Fixes variables that are ignored but have a name (instead of using _)
• Fixes types that are used but not imported
• Fixes code that uses dependencies that are not declared in our package.json

This last point is the most important one. We had some code modifying codemirror, which comes via Zazuko libs, but we never declared in package.json, using only as transitive. Now it's listed in our code as we actually import that code and modify it for our Query component.

But the most important change was replacing query-string by qs. We had both, in different parts of the code, but luckily we had unit tests covering that, so replacing was really easy and doesn't seem to break anything.

Choosing between the two was not straightforward as none is maintained by a big community or known company. After some searching, and comparing usage & downloads, looks like qs has a larger user base, and since its description mentions "security", I thought it'd be OK to keep that one and drop query-string (which might still be used in Zazuko components... although looks like they also have qs somewhere in their other transitive dependencies -- JS dependencies are complicated :sighs:)

• https://npm-compare.com/qs,query-string
• https://npm-compare.com/qs,query-string,querystring,url-parse

I grouped each change into separate commits so that I can revert/drop any if needed. Let me know if these should be squashed before the merge, and I will do so :+1:

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• [x] Tests are included.
• [ ] Documentation change and updates are provided for the Apache Jena website
• [ ] Commits have been squashed to remove intermediate development commit messages.
• [x] Key commit messages start with the issue number (GH-xxxx)

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.

[kinow]

Unit & e2e & lint & build passing locally for me (e2e and unit both failed after I first pushed, so really thankfully our JS code is reasonably well covered as I had no recollection of why the test would fail :pray: )