types.
* Add new `IdMaps` type that contains mappings to Entity from Uid, CharacterId, and
RtsimEntity.
* Add PresenceKind::LoadingCharacter variant for when the CharacterId
has not actually been confirmed to exist and belong to the logged in
client. Switches to the regular PresenceKind::Character once the
character is loaded from the database and that is used to update the
entity.
* Start refactoring `delete_entity_recorded` to check for CharacterId
and RtsimEntity values that may need to be removed from the map (just
very start, not near complete).
* Other misc tweaks.
