Bundled Themes: Adds Customizer option to show or hide author bio Twenty Twenty.

This adds an option to the Customizer that allows you to turn the author bio on or off, sitewide.

Props williampatton, nielslange acosmin, dlh.
Fixes #48550.
Built from https://develop.svn.wordpress.org/trunk@46813


git-svn-id: https://core.svn.wordpress.org/trunk@46613 1a063a9b-81f0-0310-95a4-ce76da25c4cd