Add clientSecret variable to cws-upload role

This parameter is now necessary with the new Desktop app flow for the
Chrome Web Store API keys.

Change-Id: Ied15c9e876071d488dfdbb02aa1caf9966f29ec8
diff --git a/roles/cws-upload/tasks/main.yaml b/roles/cws-upload/tasks/main.yaml
index aaab7a5..e96506a 100644
--- a/roles/cws-upload/tasks/main.yaml
+++ b/roles/cws-upload/tasks/main.yaml
@@ -14,6 +14,7 @@
           --extension-id {{ extensionId }} {{ '--trusted-testers' if (trustedTesters|bool) else '' }} \
           --source {{ zipFile }} --client-id {{ clientId|quote }} \
           --refresh-token {{ refreshToken|quote }} \
+          {% if clientSecret is defined %} --client-secret {{ clientSecret }} {% endif %} \
           2>&1 | tee cws-log.txt
     chdir: "{{ workingDirectory }}"
     executable: /bin/bash