)

Fixes #15552

Refs #15552

* chore: Remove old Markdown issue template

This template in Markdown format has been superseded by the forms in the
`.github./ISSUE_TEMPLATE` directory. When viewing this file in the
GitHub UI, it shows a warning:

> You are using an old version of issue templates. Please update to the
> new issue template workflow. [Learn more][1]

[1]: https://docs.github.com/articles/about-issue-and-pull-request-templates

* docs: Link to new issue template chooser

All of these direct links to our old Markdown-based issue templates are
broken and just lead to an empty form. I could link directly to the
relevant new yml template, but standardizing on `/issues/new/choose`
seems safer as it'll continue working even if we change the available
templates.

* feat: Implement FlatRuleTester

Implements FlatRuleTester as a way to allow devs to test their rules
against flat config.

Refs #13481

* more test fixes

* Finish tests

* Remove TODO comments

* Added subclassing tests

* Add FlatConfigArray test

* Incorporate feedback

* Fix comment

* Incorporate feedback

* Fix up typedefs

* Fix parser wrapping in all scenarios

…#15571)

…ine (#15541)

Fixes #15091

Refs #15592

…5587)

Fixes #15580

…15595)

* feat: update eslint-scope to ignore `"use strict"` directives in ES3

* update package.json with eslint-scope@7.1.1