Add gating.dev publish job

This mirrors the zuul website publishing job.

It uses a subdirectory of the zuul volume so that a new AFS volume
doesn't need to be created.  It's not actually published under the
zuul-ci.org web site.

Change-Id: I89c3a4cc0fc4880978a8d0802d43fda8dafc0cf1

playbooks/gating.dev/publish.yaml

@@ -0,0 +1,9 @@
+- hosts: localhost
+  roles:
+    - role: create-afs-token
+      when: zuul_success | bool
+    - role: upload-afs-roots
+      afs_target: "/afs/.openstack.org/project/zuul-ci.org/gating.dev/www"
+      when: zuul_success | bool
+    - role: destroy-afs-token
+      when: zuul_success | bool

zuul.d/jobs.yaml

@@ -33,6 +33,18 @@
       - secret: zuul-afs
         name: afs
 
+- job:
+    name: publish-gating.dev-website
+    description: |
+      Publishes content in artifacts/ to the gating.dev website.
+    allowed-projects:
+      - zuul/gating.dev
+    post-run:
+      - playbooks/gating.dev/publish.yaml
+    secrets:
+      - secret: zuul-afs
+        name: afs
+
 - job:
     name: build-gerrit-image
     parent: system-config-build-image-gerrit-master-base