* Fixes the totally broken UserInfo resolution in guilds.
* Adds support for USER_UPDATE from the gateway.
Design considerations behind the user cache:
* Explicitly handle deleted user IDs by short circuiting the lookup
logic and returning a singleton.
* The cache map is protected during HTTP requests to the Discord API.
* The nonexistence of a user is cached. This is to prevent excessive
requests (a user can't suddenly begin existing at a given ID).
The user cache is upserted on READY, incoming messages, backfill, etc.
In the same vein as mautrix-whatsapp, -slack and others, do not make
assumptions about how the ID is represented in the connector code. Let
the discordid package be entirely responsible.
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.
* Created a separate discordid package to avoid import cycles.
* Implemented attachment bridging. We still need to implement direct
media, but this will do for now.
* Corrected how encrypted files (e.g. embed images and attachments) were
bridged. Previously, the URL field would be empty.
Still a lot of missing pieces. Thoughts:
* Mentions to roles and custom emoji are not rendered properly. We need
to maintain our own DB.
* We might not need the "attachments" leaf package anymore? It's just
there to avoid an import cycle.
Bridging actual events (i.e. wiring up discordgo's event handlers) is
probably next.
