Fix horizon-nodejs jobs

Tox is not anymore pre-installed on the OpenDev CI images.
The file package.json needs tox, install it to fix the job.

Install it via a pre-run playbook so that this is run in addition to all
of the playbooks of the parent.

Note for the reviewer in stable/stein we run nodejs-4 jobs as runtime.
I have cherry-pick this change from master which run nodejs-10 job
but simliar changes fixes the nodejs-4 jobs So I have added pre-run
playbook for nodejs-4 job as well.

Note in stable/rocky: We used nodejs4-jobs from openstack-zuul-jobs
which consumes npm jobs from zuul-jobs. We would like to install tox
in the 'pre-run' phase in each npm job, so this commit borrows the
npm job definitions in stable/stein including the cherry-picked commit.

Conflicts:
	.zuul.yaml
Resolved automatically.

Change-Id: Icf82fa96f7d90453f78cf564c847682a286ed575
(cherry picked from commit 7cd0debebe)
(cherry picked from commit 8da0dcd212)
(cherry picked from commit 8f8ed62408)
(cherry picked from commit 301c34b911)

.zuul.yaml

@@ -32,6 +32,43 @@
     vars:
       tox_envlist: selenium-headless
 
+- job:
+    name: horizon-nodejs4-run-lint
+    parent: nodejs-run-lint
+    description: |
+      Run lint using Node 4 for horizon plugins.
+    vars:
+      node_version: 4
+    nodeset: ubuntu-xenial
+    pre-run: playbooks/horizon-nodejs/pre.yaml
+    required-projects:
+      openstack/horizon
+
+- job:
+    name: horizon-nodejs4-run-test
+    parent: nodejs-run-test-browser
+    description: |
+      Run test using Node 4 for horizon plugins.
+    vars:
+      node_version: 4
+    nodeset: ubuntu-xenial
+    pre-run: playbooks/horizon-nodejs/pre.yaml
+    required-projects:
+      openstack/horizon
+
+- project-template:
+    name: horizon-nodejs4-jobs
+    description: |
+      Run lint and test jobs using Node 4 for horizon plugins.
+    check:
+      jobs:
+        - horizon-nodejs4-run-lint
+        - horizon-nodejs4-run-test
+    gate:
+      jobs:
+        - horizon-nodejs4-run-lint
+        - horizon-nodejs4-run-test
+
 - project:
     templates:
       - openstack-python-jobs
@@ -40,7 +77,7 @@
       - periodic-stable-jobs
       - check-requirements
       - release-notes-jobs
-      - nodejs4-jobs
+      - horizon-nodejs4-jobs
     check:
       jobs:
         - horizon-openstack-tox-py27dj110

playbooks/horizon-nodejs/pre.yaml

@@ -0,0 +1,6 @@
+- hosts: all
+  roles:
+    # package.json needs to run 'tox' as command, ensure that it's
+    # installed and can be used globally.
+    - role: ensure-tox
+      ensure_global_symlinks: True