4084: adds Couchbase as JanusGraph backend

[chedim]

Issue #4084
This PR adds couchbase JanusGraph backend and search. The backend is in alfa stage and is not yet recommended for production use.

All the dependencies for the backend are either already in other poms (logback) or use licenses from category a.

Thank you for your time reviewing the PR. Suggestions on the code are highly welcomed as this was our team's first project with JanusGraph.

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[linux-foundation-easycla]

• ❌ - login: @chedim / name: Dmitrii Chechetkin . The commit (0123c4c, 9bbed63, bbd8f70, 1367f47, 6ec1d8c, c4e454c) is not authorized under a signed CLA. Please click here to be authorized. For further assistance with EasyCLA, please submit a support request ticket.

[chedim]

* [❌](https://api.easycla.lfx.linuxfoundation.org/v2/repository-provider/github/sign/1543822/77385607/4086/#/?version=2) - login: @chedim / name: Dmitrii Chechetkin . The commit ([d595025](https://github.com/JanusGraph/janusgraph/commit/d595025b681606d8a903613bb5b7e8b7ecac338d)) is not authorized under a signed CLA. [Please click here to be authorized](https://api.easycla.lfx.linuxfoundation.org/v2/repository-provider/github/sign/1543822/77385607/4086/#/?version=2). For further assistance with EasyCLA, [please submit a support request ticket](https://jira.linuxfoundation.org/servicedesk/customer/portal/4).

Working on this internally with Couchbase, should be signed within the week.

[porunov]

Thank you @chedim for the contribution!

The documentation build is failing here: https://github.com/JanusGraph/janusgraph/actions/runs/6722438476/job/18291081482?pr=4086

Most likely the new added configurations are not part of the generated configuration options. You could try executing the following to fix that failing check:

mvn clean install -DskipTests=true
git add -A
git commit --amend -s
git push -f

I also see Java 8 build fails here: https://github.com/JanusGraph/janusgraph/actions/runs/6722438464/job/18291060016?pr=4086
However, Java 11 build passes. It could mean that you used some functionality that isn't available in Java 8. You could either rewrite that functionality (Lucene2CouchbaseQLTranslator.java:[160,57]) to be compatible with Java 8 or you could wait until JanusGraph drops support for Java 8. You can see here that there is a plan to drop Java 8 support and make Java 11 minimal required Java version for JanusGraph: #4040

I also left a comment regarding CouchbaseKeyColumnValueStore implementation, but I haven't reviewed the actual code yet.

[chedim]

The CLA part is taking much longer than I've expected. Escalated it, will post an update when it is signed.