Split ext.visualEditor.mwcore out of ext.visualEditor.core

* Split files according to ve / ve-mw paths
* Split messages according to msgs-ve / msgs-ve-mw
* Update dependencies accordingly
* Remove ve-mw/ hack in makeStaticLoader.php, no longer needed

Bug: 45342
Change-Id: I6cb89606c307e27e237a1e9b56b94dfdcd310f41
Merge "Split ext.visualEditor.mwcore out of ext.visualEditor.core"