Auto-lint CiviWiki JavaScript

[brylie]

As part of our commitment to clean and maintainable code, we can lint our JavaScript. Linting will catch low-level details and encourage common coding conventions between CiviWiki developers.

Goal

Enable automated linting on the CiviWiki project.

Task

• Add ESLint metadata files to project root
• Inherit from existing ESLint style, such as Airbnb ESLint rules
• Override any of the Airbnb ESLint rules that we disagree with
• Run a project-wide lint, to see the extent of the problem
• Encourage CiviWiki developers to enable auto-linting in their IDE
• Enable auto-linting for CiviWiki GitHub pull requests

[tractaylor]

Here is a link to adding ESLint to many editors. The same page has links on how to add github prehooks for projects.
https://eslint.org/docs/user-guide/integrations

[brylie]

@JL24 can we separate this PR from your frontend refactor PR? That way we can close this issue sooner.

[brylie]

@JL24 if we don't have a status for this, should I go ahead and move it to 0.3 milestone?

[JOO33]

Closing due to solution proposed by #827. The JS related issues will be no longer relevant.