Drop old URLs from dashboard report

[chosak]

This PR modifies how Webpack is used to generate the Lighthouse dashboard, so that it drops old URLs that were tested in previous nightly runs but weren't tested in the latest run.

This doesn't remove those old reports from the repository, or from the singular reports.json file that we generate that aggregates all of the reports -- it only modifies how the dashboard website is built to exclude those results from the dashboard.

See internal https://github.local/Design-Development/Design-and-Content-Team/issues/502 for context.

I've also updated the linter config for this repo by copying the settings from https://github.com/cfpb/design-system, and cleaned up some old font files that somehow got built up over time.

Testing

Pull down this repository then run yarn && yarn serve and you'll see that your local http://127.0.0.1:8080/ server excludes URLs that aren't in the most recent test set (compare against https://cfpb.github.io/cfgov-lighthouse/).

Todos

There may be a nicer way to write the JS to implement the desired logic; @anselmbradford @contolini please feel free to school me if so.

Checklist

• PR has an informative and human-readable title
• Changes are limited to a single goal (no scope creep)
• Code can be automatically merged (no conflicts)
• Code follows the standards laid out in the development playbook
• Passes all existing automated tests

[chosak]

Hm, it actually seems like this script no longer works properly, because GH.com blocks the download of the raw file. If you look in the repo it actually commits a GH.com webpage instead of the font file. @anselmbradford @contolini what is the proper way to use the fonts? Do they need to be added to this repository as well?

[anselmbradford]

@chosak in DS v3 there is a mixin, @include licensed-font('/path/to/fonts');, for including the fonts. This would be placed in your main entry-point scss file after importing the DS. Just don't include that mixin to omit the Avenir fonts. Do you want to do the DS v3 update here, or in another PR?

[chosak]

Do you want to do the DS v3 update here, or in another PR?

@anselmbradford I've done the upgrade separately in #47, and will revisit this PR once that goes in.