Do move options checks before the move

Do move options checks before the move

This is both more correct conceptually (if the move-subpages
permission check depends on the page content, we want that to be
the content that is getting moved) and hopefully more robust
(whereas doing permission checks on a title just after having
moved it might run into issues with replication lag).

Also, permission checks can be expensive so skip the move-subpage
check when the user did not request moving subpages anyway. And
replace the deprecated method.

Bug: T225366
Change-Id: I9809b2a5bbae4006d5c5389dfd7c04f20f7da8fd