Adds new-repo template files as package_data.
When running dagster new-repo, Jinja2 does not load any template files because the template files' directory was not included as package_data in dagster/setup.py. Because of this, running dagster new-repo simply generates an empty folder.
This change adds the template files' directory dagster/generate/new_repo/ to package_data. Tests are also added to ensure that additional subfolders are generated.
Test Plan: buildkite
Reviewers: catherinewu, rexledesma, sidkmenon
Reviewed By: rexledesma
Differential Revision: https://dagster.phacility.com/D6536