Specific return types for values and values list (#53)

* Instead of using Literal types, overload QuerySet.values_list in the plugin. Fixes #43.

- Add a couple of extra type checks that Django makes:
  1) 'flat' and 'named' can't be used together.
  2) 'flat' is not valid when values_list is called with more than one field.

* Determine better row types for values_list/values based on fields specified.

- In the case of values_list, we use a Row type with either a single primitive, Tuple, or NamedTuple.
- In the case of values, we use a TypedDict.
- In both cases, Any is used as a fallback for individual fields if those fields cannot be resolved.

A couple other fixes I made along the way:
- Don't create reverse relation for ForeignKeys with related_name='+'
- Don't skip creating other related managers in AddRelatedManagers if a dynamic value is encountered
  for related_name parameter, or if the type cannot be determined.

* Fix for TypedDict so that they are considered anonymous.

* Clean up some comments.

* Implement making TypedDict anonymous in a way that doesn't crash sometimes.

* Fix flake8 errors.

* Remove even uglier hack about making TypedDict anonymous.

* Address review comments. Write a few better comments inside tests.

* Fix crash when running with mypyc ("interpreted classes cannot inherit from compiled") due to the way I extended TypedDictType.

- Implemented the hack in another way that works on mypyc.
- Added a couple extra tests of accessing 'id' / 'pk' via values_list.

* Fix flake8 errors.

* Support annotation expressions (use type Any) for TypedDicts row types returned by values_list.

- Bonus points: handle values_list gracefully (use type Any) where Tuples are returned
  where some of the fields arguments are not string literals.

django-stubs/__init__.pyi

@@ -1,7 +1,12 @@
-from typing import Any
+from typing import Any, NamedTuple
 from .utils.version import get_version as get_version
 
 VERSION: Any
 __version__: str
 
 def setup(set_prefix: bool = ...) -> None: ...
+
+# Used by mypy_django_plugin when returning a QuerySet row that is a NamedTuple where the field names are unknown
+class _NamedTupleAnyAttr(NamedTuple):
+    def __getattr__(self, item: str) -> Any: ...
+    def __setattr__(self, item: str, value: Any) -> None: ...

django-stubs/db/models/query.pyi

@@ -97,8 +97,9 @@ class QuerySet(Generic[_T, _Row], Collection[_Row], Sized):
     def raw(
         self, raw_query: str, params: Any = ..., translations: Optional[Dict[str, str]] = ..., using: None = ...
     ) -> RawQuerySet: ...
+    # The type of values may be overridden to be more specific in the mypy plugin, depending on the fields param
     def values(self, *fields: Union[str, Combinable], **expressions: Any) -> QuerySet[_T, Dict[str, Any]]: ...
-    # The type of values_list is overridden to be more specific in the mypy django plugin
+    # The type of values_list may be overridden to be more specific in the mypy plugin, depending on the fields param
     def values_list(
         self, *fields: Union[str, Combinable], flat: bool = ..., named: bool = ...
     ) -> QuerySet[_T, Any]: ...