Enable ESLint; add ESLint/Prettier to CI

[maxatdetroit]

This PR

See context in CityOfDetroit/detroitmi#1099. This PR:

• Adds ESLint to the package
• Codemods a suppression for existing lint errors (this way past errors are forgiven but no new lint errors can be added to the repo)
• Creates yarn scripts to check the lint config and format/lint source code
• Adds a GH action workflow to run format/lint on push or PR against dev branch

Note: This PR uses jscodeshift and suppress-eslint-errors to codemod Javascript to suppress ESLint errors. Then, Prettier to format the output.

$ npx suppress-eslint-errors ./src --rules=eqeqeq,no-console,no-unused-vars,prefer-const,no-case-declarations,no-unreachable,no-undef,no-empty --message="TODO: See CityOfDetroit/detroitmi#1099"
$ yarn prettier -w ./src

Testing

Run formatter, linter, and tests locally.

$ yarn lint && yarn test-storybook
Checking formatting...
All matched files use Prettier code style!
 PASS   browser: chromium  src/stories/offcanvas.stories.js
 PASS   browser: chromium  src/stories/accordion.stories.js
 PASS   browser: chromium  src/stories/modal.stories.js
 PASS   browser: chromium  src/stories/listgroup.stories.js
 PASS   browser: chromium  src/stories/card.stories.js
 PASS   browser: chromium  src/stories/dropdown.stories.js
 PASS   browser: chromium  src/stories/formcheck.stories.js
 PASS   browser: chromium  src/stories/pagination.stories.js
 PASS   browser: chromium  src/stories/formcheckgroup.stories.js
 PASS   browser: chromium  src/stories/carousel.stories.js
 PASS   browser: chromium  src/stories/loader.stories.js
 PASS   browser: chromium  src/stories/buttongroup.stories.js
 PASS   browser: chromium  src/stories/navbar.stories.js
 PASS   browser: chromium  src/stories/button.stories.js
 PASS   browser: chromium  src/stories/progress.stories.js
 PASS   browser: chromium  src/stories/formlabel.stories.js
 PASS   browser: chromium  src/stories/container.stories.js
 PASS   browser: chromium  src/stories/nav.stories.js
 PASS   browser: chromium  src/stories/alert.stories.js
 PASS   browser: chromium  src/stories/badge.stories.js
 PASS   browser: chromium  src/stories/geocoder.stories.js
 PASS   browser: chromium  src/stories/icon.stories.js
 PASS   browser: chromium  src/stories/breadcrumb.stories.js
 PASS   browser: chromium  src/stories/formcontrol.stories.js
 PASS   browser: chromium  src/stories/formselect.stories.js
 PASS   browser: chromium  src/stories/spinner.stories.js
 PASS   browser: chromium  src/stories/image.stories.js
 PASS   browser: chromium  src/stories/form.stories.js
 PASS   browser: chromium  src/stories/range.stories.js
 PASS   browser: chromium  src/stories/table.stories.js (6.543 s)

Test Suites: 30 passed, 30 total
Tests:       154 passed, 154 total
Snapshots:   0 total
Time:        7.518 s
Ran all test suites.