Add game rule options for 'The Dead Hunt'

[Xaymar]

The Dead Hunt is currently a fixed mode, but to keep things in line with the configurable approach it should be moved to gamerule options.

ph_gamerule_hiders_can_see_hiders

• Should Hiders be able to see other Hiders
• Values:
  • 0: Yes
  • #: Only after the specific state has passed.
  • -1: Never

ph_gamerule_dead_hiders_become_seekers

• Should dead hiders become seekers?
• Values:
  • 0: No
  • 1: Yes