Added Champion Medals Dependency

[druduche]

This adds an optional dependency to the Champion Medals plugin, and displays it like the other medals.
Some notes:

• We have to refresh the champion medal a couple of times, because the export function ChampionMedals::GetCMTime returns 0 both if the request failed (in which case we need to try again), and if the map has no champion medal.
• The Champion Medal is completely hidden from the display if there is none.