Description of problem:
Currently there're some VM sizes that only support UEFI image(such as DC-series, Mv2-series). And MSFT has not published UEFI RHEL image in Azure Marketplace now. Some customers don't know how to build UEFI image for Azure. If composer can support building UEFI image, it will be mush easier for customer to use such VM sizes.
Reference customer issue: https://access.redhat.com/support/cases/#/case/02500254