[GMW][AoA] Fix campaign faction code

[mmougy]

To maintain consistency with other campaign boxes: campaign cards whether player card or encounter cards should have the faction: "campaign"

following sets are currently referenced with the faction "encounter", but in fact are campaign only cards:

• Galaxy's Most Wanted

  • Challenge

• Age of Apocalypse

  • Overseer (but not Prelate, which are needed for the Apocalypse villain)
  • Mission
  • Age of Apocalypse

This is just a proposal, let me know if you agree with this, or see things other way :)