relocate dbmeta models to discordid

While we're about to introduce more metadata structs, it seems like
mautrix-slack keeps these in slackid, so let's keep ours in discordid.

pkg/connector/dbmeta.go

@@ -17,19 +17,15 @@
 package connector
 
 import (
-	"github.com/bwmarrin/discordgo"
 	"maunium.net/go/mautrix/bridgev2/database"
-)
 
-type UserLoginMetadata struct {
-	Token            string                     `json:"token"`
-	HeartbeatSession discordgo.HeartbeatSession `json:"heartbeat_session"`
-}
+	"go.mau.fi/mautrix-discord/pkg/discordid"
+)
 
 func (d *DiscordConnector) GetDBMetaTypes() database.MetaTypes {
 	return database.MetaTypes{
 		UserLogin: func() any {
-			return &UserLoginMetadata{}
+			return &discordid.UserLoginMetadata{}
 		},
 	}
 }