Expand Demo to Include Secondary Variants for Buttons + New 'Paper' Button (#2376)

* default palette helper to pick the foreground color for you when selecing a new primary or secondary background color

* fixed foreground colors to only change to generated on when selecting a new primary/secondary color

* expanded button styles to add secondary variants, added 'papaer' variant and added all these to the test app buttons page

* remove non pertinent changes

* added border to the paper button so that it can work with hovering correctly. Added color zone to buttons section for show how it works

* added back shadow darkening to paper buttons

* fixed names on flat bg buttons

* expanded the color zone to include all the top buttons for comparison

* removed color zone. moved enabled toggle to popup menu. Applied enabled to other buttons

Co-authored-by: Robert Snipe <robertjsnipe@gmail.com>

Author: rrs