[Draft] Add a draft system

[amshin98]

For open runs. A few thoughts:

• !draft then captains would react, randomly decide who's first pick who's map. Side random? This whole process can be tweaked, currently we do it where the top frags from both teams from the last game are captains and the winning captain gets to choose if they want first pick or map and side
• Bot will get list of usernames from the voice channel the captains are in
  • Quick note here, if 10 people aren't present prompt a captain to enter their @?
• Bot will dm captains when it's their turn to choose players
• Bot will dm captains when it's time to choose map/side whatever we decide

[amshin98]

Updated requirements:

• User registration and editing (rank)
• Random captain selection from a voice channel
• The lower-ranked captain gets to choose:
  • 1st pick, 2 map bans, side choice
  • 2nd pick, map choice
• Serpentine draft (1 - 2 - 2 - 2 - 2 - 1)
• Post the draft results (random order) into a text channel
  • Includes which voice channels to join and which sides