(proxy) add target for externelACL configfile

src/opnsense/service/templates/OPNsense/Proxy/+TARGETS

 rc.conf.d:/etc/rc.conf.d/squid
 squid.conf:/usr/local/etc/squid/squid.conf
 newsyslog.conf:/etc/newsyslog.conf.d/squid
+externalACLS.conf:/usr/local/etc/squid/externalACLs.conf

src/opnsense/service/templates/OPNsense/Proxy/externalACLs.conf

+#
+# Automatic generated configuration for fetching remote ACLs.
+# Do not edit this file manually.
+{% if helpers.exists('OPNsense.proxy.forward.acl.remoteACLs.blacklists') %}
+{%   for blacklist in helpers.toList('OPNsense.proxy.forward.acl.remoteACLs.blacklists.blacklist') %}
+[{{blacklist.filename}}]
+url:{{blacklist.url}}
+enabled:{{blacklist.enabled}}
+{%   endfor %}
+{% endif %}
\ No newline at end of file