The redirect to pages overview was not working because the pages overview and page edit views
share the same session namespace, and therefore the checks to see if we need to redirect to
pages overview (i.e. if there is a translated record for the current page) matched also for
the redirected request.
Fixed by checking if we already are on the CMSPagesController before redirecting to it.
Ignore the extension's init() method being called on
LeftAndMain base class,
which is the case when requests are first routed through
AdminRootController
as an intermediary rather than the endpoint controller
The site tree sidebar was not updated when creating a new translation,
due to only CurrentForm and Breadcrumbs fragments being updated by default.
Fixed by explicitly setting the X-Pjax response header to Content on
translation creation.