Deb: provide an easy way to start KasmVNC with default options

...via kasmvncserver-start.

builder/startup/deb/kasmvncserver-start

@@ -0,0 +1,22 @@
+#!/bin/bash
+
+set -e
+
+display=:1
+interface=0.0.0.0
+cert_group=ssl-cert
+
+if groups | grep -qvw ssl-cert; then
+  cat <<-EOF
+    Can't access TLS certificate.
+    Please add your user to $cert_group via 'addgroup <user> ssl-cert'
+EOF
+  exit 1
+fi
+
+vncserver $display -interface $interface
+vncserver -kill $display
+vncserver $display -depth 24 -geometry 1280x1050 -websocketPort 8443 \
+  -cert /etc/ssl/certs/ssl-cert-snakeoil.pem \
+  -key /etc/ssl/private/ssl-cert-snakeoil.key -sslOnly -FrameRate=24 \
+  -interface $interface -httpd /usr/share/kasmvnc/www