OvmfPkg: introduce QemuLoadImageLib library class

Introduce the QemuLoadImageLib library class that we will instantiate
to load the kernel image passed via the QEMU command line using the
standard LoadImage boot service.

Ref: https://bugzilla.tianocore.org/show_bug.cgi?id=2566
Signed-off-by: Ard Biesheuvel <ard.biesheuvel@linaro.org>
Reviewed-by: Laszlo Ersek <lersek@redhat.com>

OvmfPkg/OvmfPkg.dec

@@ -58,6 +58,11 @@
   #
   QemuBootOrderLib|Include/Library/QemuBootOrderLib.h
 
+  ##  @libraryclass  Load a kernel image and command line passed to QEMU via
+  #                  the command line
+  #
+  QemuLoadImageLib|Include/Library/QemuLoadImageLib.h
+
   ##  @libraryclass  Serialize (and deserialize) variables
   #
   SerializeVariablesLib|Include/Library/SerializeVariablesLib.h