Updates dependencies to fix security vulnerabilities

[anselmbradford]

Repo reports vulnerabilities for merge and cryptiles. Updates gulp-less and jest to update/remove these dependencies.

Additions

• Adds missing del dependency.

Changes

• Updates babel-jest, babel-loader, gulp-less, jest, jest-cli, jest-when, jsdom, require-dir, and through2.
• .babelrc updated to babel.config.js.
• Updates test to import dom-closest.
• Updates test simulate event syntax to es6 modules.

Testing

1. npm install
2. npm run build
3. gulp test should pass.

Screenshots

Notes

• Somehow del ended up in package-lock.json but was not in package.json, ???

[anselmbradford]

Updating stylelint from 9.3.0 to 9.9.0 breaks gulp lint, which happens automatically when package-lock is regenerated. I've downgraded it for now to fix the security vulnerabilities this PR intends to address.