arm-systemready: Introduce the Arm SystemReady layer

Add the meta-arm-systemready layer. This provides the infrastructure to
load and run the Arm SystemReady IR ACS v2.0.0 prebuilt image and
analyze the results.

The recipes included are as follows:
1. arm-systemready-firmware: Enables the ARM_SYSTEMREADY_FIRMWARE machine
   conf variable to be used to specify which firmware packages to deploy.
2. arm-systemready-ir-acs: Runs the Arm SystemReady IR ACS tests from
   the pre-built images and checks the results adhere to the specification.
3. arm-systemready-linux-distros-[debian|opensuse]: Install the distro of
   choice from CD/DVD image to target disk image.

Signed-off-by: Debbie Martin <Debbie.Martin@arm.com>
Signed-off-by: Diego Sueiro <diego.sueiro@arm.com>
Signed-off-by: Peter Hoyes <Peter.Hoyes@arm.com>
Signed-off-by: Qi Feng <qi.feng@arm.com>
Signed-off-by: Robbie Cao <robbie.cao@arm.com>
Signed-off-by: Tomás González <tomasagustin.gonzalezorlando@arm.com>
Signed-off-by: Vineeth Raveendran <vineeth.raveendran@arm.com>
Signed-off-by: Jon Mason <jon.mason@arm.com>

meta-arm-systemready/classes/extra_imagedepends_only.bbclass

@@ -0,0 +1,25 @@
+# This class is to be inherited by recipes interested in only deploying what is
+# listed in the EXTRA_IMAGEDEPENDS.
+# It is inheriting the image.bbclass to make sure that the
+# image_license.manifest is generated.
+
+IMAGE_FSTYPES = ""
+
+inherit image
+
+IMAGE_FEATURES = ""
+EXTRA_IMAGE_FEATURES = ""
+
+INHIBIT_DEFAULT_DEPS = "1"
+DEPENDS = ""
+RDEPENDS = ""
+RRECOMMENDS = ""
+
+deltask do_prepare_recipe_sysroot
+deltask do_flush_pseudodb
+deltask do_image_qa
+do_rootfs[depends] = ""
+do_rootfs[noexec] = "1"
+do_image[noexec] = "1"
+do_image_complete[noexec] = "1"
+do_build[depends] = ""