Move unittest job in-tree

Move the unittest job for this repo in-tree as Zuul v3 native job.

Change-Id: If7632956b6d28047fbacb4e9bbd416e69b0d060b

.zuul.yaml

@@ -0,0 +1,13 @@
+- job:
+    name: openstack-planet-unittest
+    description: |
+      Runs unit test on openstack-plannet project.
+    run: playbooks/unittest/run.yaml
+
+- project:
+    check:
+      jobs:
+        - openstack-planet-unittest
+    gate:
+      jobs:
+        - openstack-planet-unittest

playbooks/unittest/run.yaml

@@ -0,0 +1,11 @@
+- hosts: all
+
+  tasks:
+    - name: Run test.py
+      shell:
+        chdir: '{{ zuul.project.src_dir }}'
+        executable: /bin/bash
+        cmd: |
+          set -e
+          set -x
+          python test.py