image-build: generate root hash as an separate partition for rootfs

Generate rootfs hash data during creating the kata rootfs,
current kata image only have one partition, we add another
partition as hash device to save hash data of rootfs data blocks.

Fixes: #6674

Signed-off-by: Wang, Arron <arron.wang@intel.com>

tools/osbuilder/image-builder/Dockerfile

@@ -14,5 +14,6 @@ RUN ([ -n "$http_proxy" ] && \
         gdisk \
         parted \
         qemu-img \
+        veritysetup \
         xfsprogs && \
     dnf clean all