Backend: Define priority who turn first

[CHeMeS]

Rules for defining priority:

• if new game: at random
• if second and beyond turns:
  • priority goes to a player with lowest score
  • if score ties, priority goes to a player who lost last turn
  • if score ties and both lost, priority doesn't change.

[Konstantin Kl.]

change api schema

has_turn_priority
has_influence_priority

has_priority -> has_turn_priority

is same parameter - has_priority