Recover after #909 (#925)

* Fix stubs related to `(Async)RequestFactory` and `(Async)Client`

* Revert incorrect removal.

* Allow set as `unique_together`, use shared type alias.

* Revert `Q.__init__` to use only `*args, **kwargs` to remove false-positive with `Q(**{...})`

* Add abstract methods to `HttpResponseBase` to create common interface.

* Remove monkey-patched attributes from `HttpResponseBase` subclasses.

* Add QueryDict mutability checks (+ plugin support)

* Fix lint

* Return back GenericForeignKey to `Options.get_fields`

* Minor fixup

* Make plugin code typecheck with `--warn-unreachable`, minor performance increase.

* Better types for `{unique, index}_together` and Options.

* Fix odd type of `URLResolver.urlconf_name` which isn't a str actually.

* Better types for field migration operations.

* Revert form.files to `MultiValueDict[str, UploadedFile]`

* Compatibility fix (#916)

* Do not assume that `Annotated` is always related to django-stubs (fixes #893)

* Restrict `FormView.get_form` return type to `_FormT` (class type argument). Now it is resolved to `form_class` argument if present, but also errors if it is not subclass of _FormT

* Fix CI (make test runnable on 3.8)

* Fix CI (make test runnable on 3.8 _again_)

tests/typecheck/views/generic/test_edit.yml

@@ -61,3 +61,34 @@
 
                 class Article(models.Model):
                     pass
+
+-   case: generic_form_views_different_form_classes
+    main: |
+        from django.views.generic.edit import CreateView
+        from django import forms
+        from myapp.models import Article
+
+        class ArticleModelForm(forms.ModelForm[Article]):
+            class Meta:
+                model = Article
+        class SubArticleModelForm(ArticleModelForm):
+            pass
+        class AnotherArticleModelForm(forms.ModelForm[Article]):
+            class Meta:
+                model = Article
+
+        class MyCreateView(CreateView[Article, ArticleModelForm]):
+            def some(self) -> None:
+                reveal_type(self.get_form())  # N: Revealed type is "main.ArticleModelForm*"
+                reveal_type(self.get_form(SubArticleModelForm))  # N: Revealed type is "main.SubArticleModelForm"
+                reveal_type(self.get_form(AnotherArticleModelForm))  # N: Revealed type is "main.AnotherArticleModelForm"  # E: Argument 1 to "get_form" of "FormMixin" has incompatible type "Type[AnotherArticleModelForm]"; expected "Optional[Type[ArticleModelForm]]"
+    installed_apps:
+        - myapp
+    files:
+        -   path: myapp/__init__.py
+        -   path: myapp/models.py
+            content: |
+                from django.db import models
+
+                class Article(models.Model):
+                    pass