Add more filtering/qualification settings for giving the streaming role

[tmercswims]

Add more (and more fine-grain) ways to control who is allowed to be given the streaming role. Possibilities include:

• Allow/blocklist of games (mutually exclusive).
  • Would recheck when a streamer's game changes, to add or remove the role accordingly.
• Allow/blocklist of users (mutually exclusive).
• A role-based blocklist, i.e. give a user a role which disallows them from being given the streaming role (mutually exclusive with the existing role prerequisite functionality).
• The existing role prerequisite functionality.