OpenShift / builder should support STS authentication to AWS ECR

1. Proposed title of this feature request

OpenShift / builder should support STS authentication to AWS ECR

2. What is the nature and description of the request?

Developers building containers on STS based OpenShift clusters on AWS should be able to use STS to authenticate to Amazon Elastic Container Registry (ECR) to pull and push images during builds

3. Why does the customer need this? (List the business requirements here)

My customer is using Amazon ECR for their centralized image repository and would like to build and deploy images hosted on ECR.  However, they're unable to push images to ECR as the token rotates every 12 hours which invalidates the pull secret.

4. List any affected packages or components.

OpenShift builder (https://github.com/openshift/builder)