Add Live endpoints

[Kasea]

Would it be possible to add Live endpoints? https://developers.google.com/youtube/v3/live

[brandonbothell]

• Entities
  • LiveBroadcast
  • LiveStream
  • LiveChatMessage
  • LiveChatBan
  • LiveChatModerator
• LiveBroadcast endpoints
  • List
  • Insert
  • Update
  • Delete
  • Bind
  • Transition
• LiveStream endpoints
  • List
  • Insert
  • Update
  • Delete
• LiveChatMessage endpoints
  • List
  • Insert
  • Delete
• LiveChatBan endpoints
  • Insert
  • Delete
• LiveChatModerator endpoints
  • List
  • Insert
  • Delete
• Types
  • LiveBroadcastParts (id | snippet | contentDetails | status)[]
  • LiveStreamParts (id | snippet | cdn | status | contentDetails*)[] *docs don't state contentDetails, but I assume it's an option
  • LiveChatMessageParts (id | snippet | authorDetails)[]
  • LiveChatModeratorParts (id | snippet)[]
• Utility functions
  • OAuth#startBroadcast(...)
  • LiveBroadcast#fetchModerators(parts?: LiveModeratorParts)
  • LiveBroadcast#addModerator(...)
  • LiveBroadcast#removeModerator(...)
  • LiveModerator#remove()
  • LiveBroadcast#banUser(...)
  • LiveBroadcast#unbanUser(...)
  • LiveChatBan#unban()
  • LiveBroadcast#fetchStream(parts?: LiveStreamParts)
  • LiveBroadcast#end()
• Chores:
  • Add new entities to TypeDoc config (tsconfig.json)
  • Export new entities from entities/index.ts
  • Test new entities in their own files
    • Add these files to the exclusion in the yarn test script in package.json
  • Test OAuth class' utility function in auth.spec.ts
  • Remove coverage checks wherever required with /* istanbul ignore file */ and /* istanbul ignore next */ due to these endpoints requiring OAuth authentication
  • Re-test some OAuth methods while I'm in there

[brandonbothell]

Depends on #515 and #557