implement backup and restore draft 1

+ add extra fields for backup in favorites and scrobble data
- not yet for the playlist tracks

app/db/userdata.py

@@ -266,7 +266,7 @@ class ScrobbleTable(Base):
         return cls.insert_one(item)
 
     @classmethod
-    def get_all(cls, start: int, limit: int | None):
+    def get_all(cls, start: int, limit: int | None = None):
         result = cls.execute(
             select(cls)
             .where(cls.userid == get_current_userid())