SMS notifications: Add -X for passing extra information

While it has no immediate effect in this script itself, it allows
playbook authors to do more interesting things for generating the
message.

One could e.g. pass the team name or other meta information from
Icinga2, and then the script could forward the message to relevant chat
channels.

templates/etc/icinga2/scripts/twilio-sms-service-notification.sh.j2

@@ -31,6 +31,7 @@ Required parameters:
 Optional parameters:
   -i ICINGAWEB2URL (\$notification_icingaweb2url\$, Default: unset)
   -v (\$notification_sendtosyslog\$, Default: false)
+  -X EXTRA_DATA (\$notification_extradata\$, Default: unset)
 
 EOF
 }
@@ -61,7 +62,8 @@ urlencode() {
 {% endraw %}
 
 ## Main
-while getopts d:e:hi:l:n:o:r:s:t:u:v: opt
+EXTRA_DATA=
+while getopts d:e:hi:l:n:o:r:s:t:u:v:X: opt
 do
   case "$opt" in
     d) LONGDATETIME=$OPTARG ;; # required
@@ -76,6 +78,7 @@ do
     t) NOTIFICATIONTYPE=$OPTARG ;; # required
     u) SERVICEDISPLAYNAME=$OPTARG ;; # required
     v) VERBOSE=$OPTARG ;;
+    X) EXTRA_DATA=$OPTARG ;;
    \?) echo "ERROR: Invalid option -$OPTARG" >&2
        Usage ;;
     :) echo "Missing option argument for -$OPTARG" >&2