Added Azure pipelines to build test containers

Added a pipeline file (tests/azure/build-containers.yml) to build test
containers and upload them to quay.io. The pipeline will create
containers with IPA pre-installed for testing proposes on three
different Linux containers: CentOS 7, CentOS 8 and Fedora Latest.

molecule/resources/playbooks/prepare-common.yml

@@ -0,0 +1,29 @@
+- name: Ensure IPv6 is ENABLED
+  sysctl:
+    name: "{{ item.name }}"
+    value: "{{ item.value }}"
+    sysctl_set: yes
+    state: present
+    reload: yes
+  with_items :
+    - name: net.ipv6.conf.all.disable_ipv6
+      value: 0
+    - name: net.ipv6.conf.lo.disable_ipv6
+      value: 0
+    - name: net.ipv6.conf.eth0.disable_ipv6
+      value: 1
+
+- name: stat protected_regular
+  stat:
+    path: /proc/sys/fs/protected_regular
+  register: result
+
+- name: Ensure fs.protected_regular is disabled
+  sysctl:
+    name: fs.protected_regular
+    value: 0
+    sysctl_set: yes
+    state: present
+    reload: yes
+  when: result.stat.exists
+