Convert legacy tox jobs in-tree

This implements all step in zuulv3 migration guide [1]:

It moves the legacy tox jobs in-tree and converts them directly into
Zuul v3 native jobs.

Note that other jobs stay in project-config as common jobs.

[1] https://docs.openstack.org/infra/manual/zuulv3.html#legacy-job-migration-details

Co-Authored-By: Andreas Jaeger <aj@suse.com>
Needed-By: I210b7823bb5720d3a06cf4ac5681904c8a9c50a5
Change-Id: I3fa5ccbaf8c18c6a07bd170c3b75724be246e721

.zuul.yaml

@@ -0,0 +1,38 @@
+- project:
+    name: openstack/refstack
+    check:
+      jobs:
+        - refstack-tox-py27-func-mysql
+        - refstack-tox-py35-func-mysql
+    gate:
+      jobs:
+        - refstack-tox-py27-func-mysql
+        - refstack-tox-py35-func-mysql
+
+- job:
+    name: refstack-tox-py27-func-mysql
+    parent: openstack-tox
+    description: |
+      Run unit tests for an OpenStack Python project under cPython version 2.7.
+
+      Uses tox with the ``py27-func-mysql`` environment.
+    irrelevant-files:
+      - ^.*\.rst$
+      - ^doc/.*$
+      - ^releasenotes/.*$
+    vars:
+      tox_envlist: py27-func-mysql
+
+- job:
+    name: refstack-tox-py35-func-mysql
+    parent: openstack-tox
+    description: |
+      Run unit tests for an OpenStack Python project under cPython version 3.5.
+
+      Uses tox with the ``py35-func-mysql`` environment.
+    irrelevant-files:
+      - ^.*\.rst$
+      - ^doc/.*$
+      - ^releasenotes/.*$
+    vars:
+      tox_envlist: py35-func-mysql