Bundled Themes: Add missing RTL styles for to fix inconsistent margins on...

Bundled Themes: Add missing RTL styles for to fix inconsistent margins on `.alignwide` and `.alignfull` items.

Fixes the inconsistent margins for alignwide and alignfull classes used on Cover Block when it is the first block on a page.

Props kthmd, utz119, nikhilbhansi, and sabernhardt.
Fixes #49435.

Built from https://develop.svn.wordpress.org/trunk@47846


git-svn-id: https://core.svn.wordpress.org/trunk@47622 1a063a9b-81f0-0310-95a4-ce76da25c4cd