Ensures that these styles are loaded *after* OOUI by making
them dependent on it, unlike DesktopArticleTarget.init
which isn't.
Change-Id: Ia1fff16432d20fb56707c5e21c6a930d2478e311
VE already has a a switch icon in the options menu, so bring that
up to the main toolbar.
Append an OOUI button to the WikiEditor toolbar if present, and bind
to the same functon as the edit tab.
Bug: T49779
Change-Id: Ic1e83ea7b13c4fef68024bf05ffc244060666103
