Koji: expose boot mode in image extra metadata

Also extend the Koji test case to verify that the boot mode information
is in the build extra metadata and that it contains valid value.

Signed-off-by: Tomáš Hozza <thozza@redhat.com>

test/cases/koji.sh

@@ -163,6 +163,19 @@ function verify_buildinfo() {
             echo "Unexpected arch for '${image}'. Expected '${ARCH}', but got '${image_arch}'"
             exit 1
         fi
+
+        local image_boot_mode
+        image_boot_mode="$(echo "${image_metadata}" | jq -r '.boot_mode')"
+        # for now, check just that the boot mode is a valid value
+        case "${image_boot_mode}" in
+            "uefi"|"legacy"|"hybrid")
+                ;;
+            "none"|*)
+                # for now, we don't upload any images that have 'none' as boot mode, although it is a valid value
+                echo "Unexpected boot mode for '${image}'. Expected 'uefi', 'legacy' or 'hybrid', but got '${image_boot_mode}'"
+                exit 1
+                ;;
+        esac
     done
 }