Loosen type annotations around hook decorators

Summary: Mypy 0.812 breaks our hook decorator type annotations. This is because mypy cannot infer that pipeline defs are only used with hooks when the hook being invoked is already a hook definition.

Test Plan: mypy

Reviewers: alangenfeld, max

Reviewed By: max

Differential Revision: https://dagster.phacility.com/D8092