For each guild specified in the config, create a space and bridge all
contained text channels that the user has permissions to view.
* Finally add a custom config struct where we accept a list of guild IDs
to bridge. This is intended to be temporary as we flesh out the proper
interfaces for managing which guilds to bridge.
* Defined a custom meta type for portals that holds the containing guild
ID of the channel (if any).
* Transferred the responsibility of building a channel's ChatInfo and
ChatMemberList to the DiscordChatResync event itself.
