[Feature Request] Adding multi-region deployment support to QS artifact bucket

[veeragoni]

Currently, taskcat supports multiple region testing. But when a customer has multi-region deployment, there is no way to specify in which regions artifacts needs to be uploaded, it will upload the artifacts in the same region where it is testing the deployment. In multi region deployment using StackSets, resources(especially, ones which can't call cross region buckets) failed to get deployed in regions other than the test region. And if one includes multiple regions in a single test then taskcat execute tests in parallel across multiple regions, and fails due to duplicate resource deployments.

If we add one more config setting artifact_regions to tests and still carry out testing from one region which handles multi region deployment.

example for resources which can't call cross region buckets: aws/aws-sam-cli#2807.

This feature should solve any resource which needs same region artifacts access