Add generation for Python PEP 561 type defs

[EvanBoyle]

See this PR for pulumi/pulumi https://github.com/pulumi/pulumi/pull/3704/files

We did some work to clean up and enable mypy in pulumi/pulumi in https://github.com/pulumi/pulumi/pull/#3758, and then merged the PR to publish the type spec files.

This PR generates the same py.typed files and required config in setup.py. I tested this on the pulumi-aws package locally. Mypy runs clean on the examples repo, and I was able to solicit some mypy errors:

from pulumi_aws import s33

Evans-MBP:aws-py-s3-folder evanboyle$ mypy __main__.py 
__main__.py:6: error: Module 'pulumi_aws' has no attribute 's33'
__main__.py:8: error: Name 's3' is not defined
__main__.py:16: error: Name 's3' is not defined
__main__.py:37: error: Name 's3' is not defined
Found 4 errors in 1 file (checked 1 source file)

[github-actions]

Diff for pulumi-vault with commit cd41a34

[github-actions]

Diff for pulumi-gcp with commit cd41a34

[github-actions]

Diff for pulumi-azure with commit cd41a34

[github-actions]

Diff for pulumi-aws with commit cd41a34

[stack72]

LGTM! The diffs look so simple - nice work on this

[EvanBoyle]

Thanks @stack72. What's the process for releasing these changes and regenerating the downstream libraries?