CI: Add cover jobs

Change-Id: Id4db315bffacb662c61baab9508aecee287a2dc2

.coveragerc

@@ -4,3 +4,4 @@ source = magnum_capi_helm
 
 [report]
 ignore_errors = True
+show_missing = True

.zuul.yaml

@@ -1,4 +1,16 @@
 ---
+- project-template:
+    name: openstack-cover-jobs-magnum
+    description: |
+      The standard openstack-cover-jobs but with magnum added as a
+      required-projects. This checks out the project code and allows
+      tox_install_siblings to use it when building the venv.
+    check:
+      jobs:
+        - openstack-tox-cover:
+            required-projects:
+              - openstack/magnum
+
 - project-template:
     name: openstack-python3-jobs-magnum
     description: |
@@ -51,4 +63,5 @@
 - project:
     queue: magnum
     templates:
+      - openstack-cover-jobs-magnum
       - openstack-python3-jobs-magnum