Create 'mover' usergroup at Italian Wikipedia

This change introduces a new user group 'mover'
and removes the existing 'filemover' user group.

Rights assigned to 'mover' group:
-movefile
-move-subpages
-suppressredirect

Users can be assigned to this group by sysops
and can be removed by bureaucrats.

Bug: T102770
Change-Id: I9d34c0ef7944c5acddf1911d18e93bc8b1361070