OvmfPkg/QemuVideoDxe: parse edid blob, detect display resolution

OvmfPkg/QemuVideoDxe: parse edid blob, detect display resolution

Check whenever an EDID blob is present.  In case it is get the display
resolution from it.  Unless PcdVideoResolutionSource indicates the
display resolution has been set already, update
PcdVideoHorizontalResolution and PcdVideoVerticalResolution accordingly.
Also add the resolution to the mode list.

This will make OVMF boot up with the display resolution configured by
QEMU, which is 1280x800 by default.  The resolution can be set using the
xres and yres properties.  Here is an example for FullHD:

qemu-system-x86_64 -device VGA,xres=1920,yres=1080

Ref: https://bugzilla.tianocore.org/show_bug.cgi?id=3778
Ref: https://bugzilla.redhat.com/show_bug.cgi?id=1749250
Signed-off-by: Gerd Hoffmann <kraxel@redhat.com>
Acked-by: Ard Biesheuvel <ardb@kernel.org>