WRITE_NEW mode seems to be working well on Wikimedia sites. Let's change
the default to MIGRATION_NEW so existing installs and Wikimedia CI will
start using the new code rather than the old.
This also fixes some unit tests that were broken with MIGRATION_NEW, and
updates some that were forcing MIGRATION_OLD to force MIGRATION_NEW
instead.
Bug: T166733
Change-Id: I7bf4ad0105dd1f6cc49eba3ddcb7a51badcd5ed3
Depends-On: I30f7cdcc3875f3f7af116c1e41e88f62ab9e91d0
During development a lot of classes were placed in MediaWiki\Storage\.
The precedent set would mean that every class relating to something
stored in a database table, plus all related value classes and such,
would go into that namespace.
Let's put them into MediaWiki\Revision\ instead. Then future classes
related to the 'page' table can go into MediaWiki\Page\, future classes
related to the 'user' table can go into MediaWiki\User\, and so on.
Note I didn't move DerivedPageDataUpdater, PageUpdateException,
PageUpdater, or RevisionSlotsUpdate in this patch. If these are kept
long-term, they probably belong in MediaWiki\Page\ or MediaWiki\Edit\
instead.
Bug: T204158
Change-Id: I16bea8927566a3c73c07e4f4afb3537e05aa04a5
