Pytype

Updates:
* Performance improvements:
* Speed up Variable.Bindings by using the reachability analyzer.
* Implement literal erasure for List and Tuple.
* Add support for analyzing python scripts.

Bug fixes:
* Fix bug in pytype's handling of overloads.
* Fix timeout caused by name clash between a module and a package.
* Limit the scope of module aliases in load_pytd.
* Handle generic dataclasses in fiddle configs.
* Support referring to a class via an alias in a pyi file.
* Fix a crash when pattern matching on collections.abc classes.
* Handle nested classes better in the LookupExternalTypes visitor.
* Improve matching of typing names in the pyi parser.

Updates:
* When checking for unmatched typevars in defs, use a separate message for bare
generic aliases.
* If an overridden method changes the name of a posarg, check posarg count but
not types.

Bug fixes:
* Fix for number of bindings when constant folding long lists.

Updates:
* Performance optimizations:
* Cache the `NestedAnnotation.formal` property.
* Speed up `LateAnnotation.__getattribute__`.
* Speed up abstract_utils._isinstance.
* Add support for dataclasses.KW_ONLY.
* Bump networkx version requirement to pick up a matplotlib compatibility fix.

Bug fixes:
* Fix a string manipulation bug in LookupScopedNames.
* Fix a crash in the fiddle overlay when instantiating a function-based config.
* Allow constants as defaults in pyi files.

Updates:
* Remove pytype's copy of the _ctypes stub.

Bug fixes:
* Remove expensive copy.deepcopy call from the pytd printer.
* Track default (_) cases in match statements in the director.

Updates:
* Add a block graph visualiser.
* Remove the --always-use-return-annotations flag. Its behavior is now enabled
by default.

Bug fixes:
* Add pattern matching for builtins.
* Keep track of already-seen cases when analysing the same match statement
twice.
* Support `total=False` on imported TypedDicts.
* Use SupportsIndex in some builtins.
* Improve handling of dataclasses and attrs in pyi files.
* Fix inferred yield type for YIELD_FROM opcode.

Updates:
* Add an overlay for the third party fiddle configuration library.
* Add feature to not replace None with Any when it is the only value.

Bug fixes:
* Fix pattern matching over imported enums.
* Track the variable name for annotated assignments in the director.
* Don't replace late annotations with Any in class definitions.
* Preserve TypedDict instances in TypeVar substitutions.
* Delegate getattr on pyi classmethods and staticmethods to underlying method.
* Support late annotations as parameters for user-defined generic classes.
* Fix a nondeterminism bug in pytype.
* Fix a latent type error in the typing.TypedDict overlay.
* Fix a crash caused by failing to catch [bad-concrete-type].
* Update memview stubs to be closer to API.