add add_link.py and improve hamndling of MediaFile

kontor-api/src/schema/media/file.py

@@ -1,12 +1,11 @@
 from datetime import datetime
-from typing import AnyStr
 
 from src.db.models.media import MediaFile
 from pydantic import BaseModel
 
 
 class MediaFileResponse(BaseModel):
-    id: AnyStr
+    id: str
     title: str | None = None
     file_name: str | None = None
     cloud_link: str | None = None