Create general font view for D8

Similar to the D7 version, with here's some changes:

• Fonts are entities, so we can easily do a teaser view and control output in the view mode settings
• Views are saved in config now, so providing a default view is just copying the config file to the module config directory
• We'll eventually want to do inline font application/config forms, so that will likely change the interface a bit, though we'll still need to be able to click through to that form so it's still functional sans-JS. A lot of people totally missed the little gear icon in D7, so a text link ("apply"?) would probably be better.
• The exposed filter form needs to work better at smaller screen sizes. Maybe it should always be vertical, not horizontal, and then it could just move from multi-column to single-column on mobile sizes?

A very basic view is in fontyourface_ui. Still needs a lot of work.

Critical priority means release blocker.