Support != in action.group.include conditions

[janbridley]

Description

While the condition grammar can express != fairly easily, it would be nice to have an option to simply exclude a particular key. This PR aims to do that, although it's quite possible I've missed something as I'm not particularly familiar with the internals of row.

Motivation and context

Resolves #???

How has this been tested?

Added test for neq.

Checklist:

• I have reviewed the Contributor Guidelines.
• I agree with the terms of the Row Contributor Agreement.
• My name is on the list of contributors (doc/src/contributors.md) in the pull request source branch.
• I have added a change log entry to doc/src/release-notes.md.

[joaander]

!= is a good comparison to add.

Changes needed before merge:

• Complete the checklist (contributor name and change log are not done).
• Add a test evaluate_json_comparison(&Comparison::NotEqualTo, &Value::from(10), &Value::from(5)) to ensure the new check works in both directions.
• List the new operator in tutorial/group.md as well so it will appear in the tutorial: https://row.readthedocs.io/en/1.0.1/guide/tutorial/group.html

[joaander]

Please complete the remaining tasks. This will be a helpful new feature for row users.

[joaander]

@janbridley I think this is a good addition. Please complete the remaining PR checklist tasks so that I can merge it.

[joaander]

Thanks!