add cookiecutter package, add extensions dev new smoke test

[alexrashed]

Motivation

localstack extensions dev new depends on cookiecutter/cookiecutter in order to create a project stub based on the cookie cutter template in localstack/localstack-extensions.
However, the PyInstaller binary build of our LocalStack CLI does not add the cookiecutter package to the dependencies, which is why it's not added to the final package. This results in the following error when using localstack extensions dev new with the binary build of the LocalStack CLI:

$ localstack extensions dev new
Error: this command requires the cookiecutter CLI, please run:
pip install cookiecutter

This PR fixes this issue by adding the package to the binary build.

Changes

• Adds cookiecutter to the requirements
• Adds a hook to allow building the cookiecutter package with pyinstaller.

Testing

• Adds a new step for Pro smoke tests which checks that localstack extensions dev new with all-defaults results in a newly generated python project containing the LocalStack extensions boilerplate code.

[thrau]

thanks for adding this!