Feature request: support module-level `__getattr__` in stubs

[rchen152]

Describe the Bug

A top-level __getattr__ definition in a stub file indicates that the file is incomplete and any name can be accessed (https://typing.python.org/en/latest/guides/writing_stubs.html#incomplete-stubs). Pyrefly doesn't currently respect this.

Sandbox Link

https://pyrefly.org/sandbox/?project=N4IgZglgNgpgziAXKOBDAdgEwEYHsAeAdAA4CeS4ATrgLYAEYuudENxulALnQBogA0IMpRhgopQp1pQKAYjoAFUiLGk6aLHnx0AxrnSQA5gFdKqThH2EAOunkBlGDDoALTp2JxEAem-DR4oQcht4w6N6YuDpw3noGECZmFvreDBx0qABuqNCo2LC6%2Bkam5pbodLjEyehwNuhknC76ALSZMJRwZXQAvHTWIADMhACMAEz9tgLgTCSkEBRg1PScpMQQ6IYsbBzcAILopNaUtpiidAD654YwnOaclJcAFOioNDAAlHTNAHx0%2B6SIOiEYEgAC%2BglQOgsbQAYtAYBQNDgCLMwUA

(Only applicable for extension issues) IDE Information

No response