XWIKI-11251: Handle #xwikicontent as a column in the layout grid

* Adding a row container for #xwikicontent, that now is a column
* Indenting

(cherry picked from commit 1da37a417fcf9d52705f1b35468014cd93550b4a)

Conflicts:
	xwiki-platform-core/xwiki-platform-flamingo/xwiki-platform-flamingo-skin/src/main/resources/flamingo/contentview.vm