Rework how we pass arguments to QEMU, provide a wks.in file

Rework how we pass arguments to QEMU, provide a wks.in file

- The official hook for changing the resolution we tell QEMU is
  UVESA_MODE so change agl_qemux86-64.inc to set the value there rather
  than override the whole of QB_KERNEL_CMDLINE_APPEND.
- Make agl_qemux86-64.inc further append what's needed to
  QB_KERNEL_CMDLINE_APPEND as APPEND isn't used in the filesystem images
  we create anymore.
- Create a directdisk.wks.in file that will (a) use --use-uuid and not
  force /boot to be looked for on /dev/sda1 (when it will _NOT_ be) and
  (b) evaluate QB_KERNEL_CMDLINE_APPEND to determine what the bootargs
  to the kernel will be.

Change-Id: I49894d70e6c0010e0907b72f19fcc8fb0917e34a
Bug-AGL: SPEC-1301
Signed-off-by: Tom Rini <trini@konsulko.com>