Previously, the ve-mw/init/ directory contained two kinds of files:
those that were used when initializing VE, and those that may be
loaded even if VE is not going to be initialized at all. The latter
kind must not use the `ve` global variable.
After moving those files to ve-mw/preinit/ we can enforce this with
.eslintrc.json in that directory. This would have prevented T228684.
(Technically they merely must not use `ve.init`, and may use `ve`,
but that's harder to enforce. We should instead move the few non-init
methods out of `ve`: now, track, trackSubscribe, trackSubscribeAll).
Also, group some files under ve-mw/init/: targets/ now (only)
contains ve.init.mw.Target and its subclasses, apiresponsecache/
now contains ve.init.mw.ApiResponseCache and its subclasses.
Bug: T228684
Change-Id: I945249a27f6a0fa10a432d5c5dc57bc7e0461fd8
