[Blueprint] Close #2723: add export feature for blueprint and artifacts

[08nholloway]

---

This checklist is used to make sure that common guidelines for a pull request are followed.

General Guidelines

• Have you run azdev style <YOUR_EXT> locally? (pip install azdev required)
• Have you run python scripts/ci/test_index.py -q locally?

[fengzhou-msft]

Nice work! Please add a release note in HISTORY.rst and bump the minor version in setup.py.