Since T348286, OOUI elements like .oo-ui-windowManager and
.oo-ui-defaultOverlay are attached to the new #mw-teleport-target
element, and styles like font-size should be changed on that element,
so that they will also apply to Codex dialogs in the future.
Bug: T348287
Change-Id: I2cbd3298ed2494c68a2db1409e2975093e36d488
Also delete unused images, since even if something is
somewhere using them anyway (looked, couldn't find
anything), it wouldn't be able to find them in the new
image location regardless.
Wiki.png, magnify, and link are all part of core and have
been for some time.
Change-Id: Id7a02155a5f1b207908c9c0c8f7519b6d3f9a886