Check in stubs folder. Closes #46.

[erikrose]

I figure putting this in testing/ suggests what it's supposed to be used for. And we'll document it, of course.

It not being an importable package, it won't inflate any built components.

[posborne]

Including the stubs make sense to me; I lean toward including them at fastly_compute/stubs if it doesn't cause issues since use of stubs may not strictly be a testing concern.

The stubs/ directory within a package is a somewhat convention within mypy: https://mypy.readthedocs.io/en/stable/stubs.html. I need to read up on PEP 561 in some more details. https://peps.python.org/pep-0561/

It's easy enough to move the directory if we change our mind after reading a bit more, so I'm OK with moving this forward as-is.

[erikrose]

PEP 561 and the mypy page refer to old-style stubs, which externally supplied type info to libs that didn't ship with their own annotations. They had .pyi extensions.

But yeah, anywhere reasonable within the package is fine with me. We don't really have to solidify the decision until beta. Thanks for the quick review!