move generated stubs to separate directory, too messty

django-stubs-generated/db/models/fields/mixins.pyi

@@ -0,0 +1,16 @@
+from typing import Any, Optional
+
+from django.db.models.base import Model
+
+NOT_PROVIDED: Any
+
+class FieldCacheMixin:
+    def get_cache_name(self) -> None: ...
+    def get_cached_value(
+        self, instance: Model, default: Any = ...
+    ) -> Optional[Model]: ...
+    def is_cached(self, instance: Model) -> bool: ...
+    def set_cached_value(
+        self, instance: Model, value: Optional[Model]
+    ) -> None: ...
+    def delete_cached_value(self, instance: Model) -> None: ...