chore: prefer woff and woff2

[DanielRuf]

Currently all old font formats of the default font(s) are used but are not needed.

IE9+ and others support woff and woff2 which are much smaller and better.

See https://caniuse.com/#feat=woff

[VladimirZaets]

Hi, @DanielRuf , thank you for collaboration, good job!

[DanielRuf]

1. Magento\Framework\View\Asset\MinifierTest::testCSSminLibrary
   Minified CSS differs from initial minified CSS snapshot. Ensure that new CSS is fully valid for all supported browsers and replace old minified snapshot with new one.

How can I create a new snapshot?
It's currently a bit unclear as the Grunt tasks do not seem to automate this.

[magento-engcom-team]

Hi @DanielRuf. Thank you for your contribution.
Changes from your Pull Request will be available with the upcoming 2.2.6 release.

Please, consider to port this solution to 2.3 release line.
You may use Porting tool to port commits automatically.