Add helper to enable both displays in qemu

This supports testing the drm-leasemanager in qemu.

We can bring up two outputs, but the 2nd output is disabled until it is connected.
See https://jira.automotivelinux.org/browse/SPEC-4464
and
https://gitlab.com/qemu-project/qemu/-/issues/1107

This adds a helper tool that will bring up the 2nd screen.

Bug-AGL: SPEC-4464
Change-Id: I145a1b947916337daa9c8e7aed38e64919b35df8
Signed-off-by: Jan-Simon Moeller <jsmoeller@linuxfoundation.org>