v2.1.0: Stripe webhooks, authorization, and multiple deployment improvements, bug fixes

This release adds support for:

• Multiple deployments with different vendor prefixes on a single AWS account. This is useful for the development of multiple apps within a single AWS account.
• Support for specifying a tenantId claim in the access tokens and using them for making the authorization decisions. This allows tokens created using yarn ops jwt -c tenantId=... to impersonate a given tenant of the system and is useful for testing. NOTE Relying on this feature for customer support activities is a bad security practice.
• Support for distinct URLs for test and production Stripe webhooks.

Bug fixes:

• Improved documentation for setting up AWS CLI credentials (thanks @mauricioschneider).
• Fix the URLs in the samples within the documentation (thanks @ondrej).
• Improve error messages for LetsGo CLI commands that accept a choice of artifacts as an option.
• Fix #14. Enable building LetsGo Docker images on Apple silicone machines. (thanks @mauricioschneider).
• Fix #17. Adjust IAM permissions to allow the worker to enqueue subsequent work for itself.
• Fix #18. Fix the expiry time of the access token created for the worker to avoid a race condition in calling the HTTP API from within the worker.