Store role list in database and convert role mentions into a readable format

database/database.go

@@ -22,6 +22,7 @@ type Database struct {
 	Reaction *ReactionQuery
 	Emoji    *EmojiQuery
 	Guild    *GuildQuery
+	Role     *RoleQuery
 }
 
 func New(baseDB *dbutil.Database) *Database {
@@ -59,6 +60,10 @@ func New(baseDB *dbutil.Database) *Database {
 		db:  db,
 		log: db.Log.Sub("Guild"),
 	}
+	db.Role = &RoleQuery{
+		db:  db,
+		log: db.Log.Sub("Role"),
+	}
 	return db
 }