Migrated leaderboard to NASA-AMMOS org

[riverma]

Purpose

• Migration of leaderboard code and results to a stand-alone repository
• Why?
  • Central hosting of leaderboard generation code allows SLIM best practice checks to be run against non-Unity projects as well
  • Hosting the Unity leaderboard here allows the Unity leaderboard to be up-to-date with respect to the latest leaderboard improvements and changes more easily

    Proposed Changes

• [CHANGE] Migrated all leaderboard code (as well as Unity's leaderboard page) to https://github.com/NASA-AMMOS/slim-leaderboard

  Issues

• N/A

  Testing

• Tested links locally