build-qemu-robot-docker: Support proxy
build-qemu-robot-docker: Support proxy

Make build-qemu-robot-docker.sh support proxy.

Signed-off-by: Lei YU <fc52a17c06c071ee7cd115c972235443e2107013@bytedance.com>
Change-Id: Id15b9c0273f8721c97556b166e4184c5bd7840d3

openbmc/openbmc-build-scripts,openbmc/openbmc-build-scripts