State Discord notifications and more

[ondryaso]

This PR:

• Separates webhook logic from DiscordBoardGamesNotificationHandler into an abstract DiscordWebhookClient
• Adds Discord notifications about state changes (in FitwideDiscordTransitionHandler and SuDiscordTransitionHandler)
  • Adds a nullable DiscordNotificationId attribute to PlannedState (running migrations is required)
• Fixes a few bugs in ClubStateService
• Enables unauthenticated SMTP connections (this is needed in production)
• Moves --migrate-db and --bootstrap-db to Main
  • This is needed because both our background services would run before the migrations and thus throw an exception
• Adds a simple publishing script