Rewrites and redirects per environment

**Is your feature request related to a problem? Please describe.**
As a developer, I want to test redirection rules for only dev environment so that I do not affect production environment.

**Describe the solution you'd like**
Having an option "environment" to rewrite and redirects.

**Alternative solutions**
1) Having an environment variable
2) Set environment query string with https://github.com/aws-amplify/amplify-console/issues/97#issuecomment-906172145

**Additional context**
A user wants to build an app on ECS on the same domain with the other app on ECS. They are considering to design Multi Origin with CloudFront, but it'd be easier if Rewrites and redirects can connect to an endpoint of ALB. In addition, their Amplify app has dev, prod environment and using environment variable to set into target address would unblock the challenge.