Here we upgrade the AWS Go SDK to 1.12.27 and AWS provider to include terraform-providers/terraform-provider-aws#1608.
This includes the capability to use named credentials profiles from the `~/.aws/credentials` file to authenticate to the backend.
* provider/aws: New resource codepipeline
* Vendor aws/codepipeline
* Add tests
* Add docs
* Bump codepipeline to v1.6.25
* Adjustments based on feedback
* Force new resource on ID change
* Improve tests
* Switch update to read
Since we don't require a second pass, only do a read.
* Skip tests if GITHUB_TOKEN is not set
Brian Flad