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/templates/unifi.nginx.conf.j2

@@ -0,0 +1,9 @@
+location / {
+    proxy_pass https://127.0.0.1:8443/;
+    proxy_ssl_verify off;
+    client_max_body_size 50m;
+    proxy_set_header Host $host;
+    proxy_set_header X-Forwarded-Proto $scheme;
+    proxy_set_header X-Real-IP $remote_addr;
+    proxy_set_header X-Forwarded-For $proxy_add_x_forwarded_for;
+}