az acr command to check the size of an image or list the size of all the images in repository

**Is this a BUG REPORT or FEATURE REQUEST?**:

FEATURE REQUEST

**What happened?**:

Seems like we are using more than allocated space for ACR in one of our subscriptions, since we dont have control over who pushes the images to ACR. We would like to know if there is a way on which image is taking up most of the space.

**What did you expect to happen?**:

I would like to add a feature request, so that we can have . az acr list image size --all -n <> --repository <>. something like that. which can help us determine who is taking up the space and see if that is really necessary.

**Environment (if applicable to the issue)**:
- Azure CLI
- Powershell

If any information is a concern to post here, you can create a [support ticket](https://azure.microsoft.com/en-us/support/create-ticket/) or send email to acrsup@microsoft.com.