Reverse the dependency for mediawiki.language.data

Reverse the dependency for mediawiki.language.data

* Previously mediawiki.language.data depended on mediawiki.language,
  making any module using langauge data having to explicitly define
  it as a dependency. This is not good. We should abstract the data
  generation part and for the users of the module.
  mediawiki.language should take care of having the required data.

* So, reversing the dependency so that mediawiki.language depends on
  mediawiki.language.data. Then a simple dependency declaration with
  "mediawiki.language" is enough to have associated data available.

This supersedes change set I810fb0a5

Change-Id: Iede836bb3e2fd700cb7c58caeebe9ec2e0043dfb