Ability to tag a local image in order to push to remote registry without requiring rebuild

Workflow: 1. Build local image and tag with e.g build number. 2. Push to internal registry with build number. 3. Tag and push build number local image with tag latest.

Currently between step 2 and 3 another docker build task is required when using a custom repository. You have to build with the registry specified in order to push to it in the push to registry task.