Bundled Themes: Twenty Twenty add theme support for responsive embeds.

Adds the call to `responsive-embed` theme support in order to fix issues with facebook embeds not being responsive at certain screen widths.

Props williampatton, nielslange.
Fixes #48552.
Built from https://develop.svn.wordpress.org/trunk@47135


git-svn-id: https://core.svn.wordpress.org/trunk@46935 1a063a9b-81f0-0310-95a4-ce76da25c4cd