Skin: Remove more use of QuickTemplate::setRef()

Skin: Remove more use of QuickTemplate::setRef()

Follows-up 2c01147c13be.

* language_links: The local array variable is only used once to
  obtain the value from Skin::getLanguages(), and then never passed
  elsewhere or otherwise potentially changed, so this reference
  doesn't seem useful.
  The getLanguages() method itself also creates a new array every
  time it is called, so the reference from there can't change either.

* Same for content_navigation and content_actions. These are never
  modified, and the method that returns the array creates a new one
  on each call.
  Follows-up r3014 (f4755755daed1f8).

* Same for bodytext.

Presumably these were only set as references to save memory.

Bug: T140664
Change-Id: I1224a7a89c1d7ad05c73132ff73299fd78ade7fb