Use Projen and include workflows-sdk

[aj-aws]

Description

This change updates the repository to use projen and adds the workflows-sdk to the main branch.

Testing

yarn build

Checklist

I have:

• [ ] Added new automated tests for any new functionality
• [x] Run yarn build

Licensing statement (do not modify)

By submitting this pull request, I confirm that you can use, modify, copy, and redistribute this contribution, under the terms of your choice.

[alexforsyth]

Lgtm