Update: Rule "eqeqeq" to have more specific null handling (fixes #6543)

[sstur]

What issue does this pull request address?
This fixes issue #6543: Enforce use of non-strict equality when comparing to null

What changes did you make? (Give an overview)
This changes the rule eqeqeq so that it optionally takes a second argument which should be an object with one supported property: {"null": "always|never|ignore"}. This lets us configure very specific handling of null literals. This also deprecates the option "allow-null" in favor of this more explicit config.

Is there anything you'd like reviewers to focus on?
Please let me know if my code style fits your project and give me any feedback about my style of describing this feature in the readme. If you prefer better wording/terminology, comment with specifically how you would like to have it worded and I'll update the PR.

Thanks!

[mention-bot]

@sstur, thanks for your PR! By analyzing the annotation information on this pull request, we identified @vitorbal, @pedrottimark and @BYK to be potential reviewers

[eslintbot]

Thanks for the pull request, @sstur! I took a look to make sure it's ready for merging and found some changes are needed:

• The commit summary needs to begin with a tag (such as Fix: or Update:). Please check out our guide for how to properly format your commit summary and update it on this pull request.
• Pull requests with code require an issue to be mentioned at the end of the commit summary, such as (fixes #1234). Please update the commit summary with an issue (file a new issue if one doesn't already exist).

Can you please update the pull request to address these?

(More information can be found in our pull request guide.)

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[eslintbot]

LGTM

[platinumazure]

@sstur Looks like this will need to be rebased. Can you rebase the branch? Let us know if you need help with that.

[eslintbot]

LGTM

[sstur]

@platinumazure: Done. Thanks!

[platinumazure]

Suggest adding a comma after "second argument"- feels like that might read better.

[platinumazure]

Left a few minor comments. Thanks for submitting the PR, can't wait to see it land.

[sstur]

Those all seem very doable. I'll get an update out...

[eslintbot]

LGTM

[eslintbot]

LGTM

[sstur]

@platinumazure: done.

[ilyavolodin]

One comment about schema, otherwise LGTM.

[gyandeeps]

LGTM, I think we should go with the proposed schema change.

[eslintbot]

LGTM

[sstur]

Thanks @gyandeeps and @ilyavolodin! Done as proposed by @mysticatea.

[gyandeeps]

LGTM 👍
Thanks for contributing @sstur