Implement STS in AWS EFS CSI driver operator, as described in the epic / https://docs.google.com/document/d/1iFNpyycby_rOY1wUew-yl3uPWlE00krTgr9XHDZOTNo/edit / https://github.com/openshift/enhancements/pull/1339 

Exit criteria:

• Verify that AWS EBS CSI driver operator can be installed on STS-enabled cluster as described in the enhancement, especially this part:
  1. user goes to console and starts [AWS EFS] operator install
  2. console detects token-based (STS) cluster, and token-based-supporting operator
  3. console prompts user to create roles+supply ARN-type string
  4. (the rest is done by OCP, in the end the user has EFS driver installed and it can provision / mount / unmount / delete EFS PVs)
• Verify that docs has been updated to the new workflow.