unifi: Deploy Unifi Network controller

Since Ubiquiti only publishes Debian packages for the Unifi Network
controller software, running it on Fedora has historically been neigh
impossible.  Fortunately, a modern solution is available: containers.
The *linuxserver.io* project publishes a container image for the
controller software, making it fairly easy to deploy on any host with an
OCI runtime.  I briefly considered creating my own image, since theirs
must be run as root, but I decided the maintenance burden would not be
worth it.  Using Podman's user namespace functionality, I was able to
work around this requirement anyway.

roles/unifi/handlers/main.yml

@@ -0,0 +1,8 @@
+- name: reload systemd
+  systemd:
+    daemon_reload: true
+
+- name: restart unifi
+  systemd:
+    name: unifi
+    state: restarted