r/dch-selinux: Install dch-selinux package

The *dch-selinux* package contains customized SELinux policy modules.
I haven't worked out exactly how to build an publish it through a
continuous integration pipeline yet, so for now it's just hosted in my
user `public_html` folder on the main file server.

roles/dch-selinux/tasks/main.yml

@@ -0,0 +1,16 @@
+- name: ensure dch-selinux repository is installed
+  copy:
+    src: >-
+      {{ ansible_distribution }}.repo
+    dest: /etc/yum.repos.d/dch-selinux.repo
+    mode: u=rw,go=r
+  tags:
+  - yum-repo
+  - install
+
+- name: ensure dch-selinux is installed
+  package:
+    name: dch-selinux
+    state: present
+  tags:
+  - install