SpecialCentralAutoLogin: Move javascript to separate files for linting

* To make this stuff easier to edit, maintain, use and lint; move
  them to actual javascript files. They'll be automatically
  picked up by the jshint check for this repository from now on.

* Set up logic to serve these minified. Based on ResourceLoader's
  internals (this should be abstracted by MediaWiki core ideally,
  but kept it as simple as possible for now).

* Added a few line breaks to separate the different concatenated
  scripts from each another.

Change-Id: I132ea06f82ad74ba51186e698dbb917e931534a2