Add test to import all modules to check validity of stubs (#56)

* add import_all.test builder

* fix errors

* fix typechecking errors

* fix migrations typechecking

django-stubs/contrib/auth/context_processors.pyi

@@ -1,22 +1,20 @@
-from typing import Any, Dict, Optional, Union
+from typing import Any, Dict
 
-from django.contrib.auth.models import AnonymousUser, User
 from django.http.request import HttpRequest
-from django.utils.functional import SimpleLazyObject
 
 class PermLookupDict:
-    app_label: django.utils.safestring.SafeText
-    user: SimpleLazyObject
-    def __init__(self, user: SimpleLazyObject, app_label: str) -> None: ...
+    app_label: str
+    user: Any
+    def __init__(self, user: Any, app_label: str) -> None: ...
     def __getitem__(self, perm_name: str) -> bool: ...
     def __iter__(self) -> Any: ...
     def __bool__(self) -> bool: ...
 
 class PermWrapper:
-    user: SimpleLazyObject = ...
-    def __init__(self, user: Union[AnonymousUser, User]) -> None: ...
+    user: Any = ...
+    def __init__(self, user: Any) -> None: ...
     def __getitem__(self, app_label: str) -> PermLookupDict: ...
     def __iter__(self) -> Any: ...
-    def __contains__(self, perm_name: Union[bool, str]) -> bool: ...
+    def __contains__(self, perm_name: Any) -> bool: ...
 
-def auth(request: HttpRequest) -> Dict[str, Union[PermWrapper, AnonymousUser, User]]: ...
+def auth(request: HttpRequest) -> Dict[str, Any]: ...