remove catch-all __getattr__ for Manager, fix some issues with manager methods (#227)

test-data/typecheck/managers/querysets/test_basic_methods.yml

@@ -28,4 +28,20 @@
                 from django.db import models
 
                 class Blog(models.Model):
-                    created_at = models.DateTimeField()
+                    created_at = models.DateTimeField()
+
+
+-   case: queryset_missing_method
+    main: |
+        from myapp.models import User
+        reveal_type(User.objects)  # N: Revealed type is 'django.db.models.manager.Manager[myapp.models.User]'
+        User.objects.not_existing_method()  # E: "Manager[User]" has no attribute "not_existing_method"
+    installed_apps:
+        - myapp
+    files:
+        -   path: myapp/__init__.py
+        -   path: myapp/models.py
+            content: |
+                from django.db import models
+                class User(models.Model):
+                    pass

test-data/typecheck/managers/test_managers.yml

@@ -309,6 +309,7 @@
         from myapp.models import User
         reveal_type(User.objects.get())  # N: Revealed type is 'myapp.models.User*'
         reveal_type(User.objects.select_related())  # N: Revealed type is 'myapp.models.User_MyManager[myapp.models.User]'
+        reveal_type(User.objects.get_instance())  # N: Revealed type is 'builtins.int'
     installed_apps:
         - myapp
     files:
@@ -317,6 +318,7 @@
             content: |
                 from django.db import models
                 class MyManager(models.Manager):
-                    pass
+                    def get_instance(self) -> int:
+                        pass
                 class User(models.Model):
                     objects = MyManager()