security/openvpn-legacy: fill in the code

This is basically it for the plugin.  The harder part is taking care
of the core support and detecting the plugin use.

PR: https://github.com/opnsense/core/issues/8347

security/openvpn-legacy/src/opnsense/mvc/app/models/OPNsense/OpenVPN/ACL/ACL.xml

@@ -0,0 +1,14 @@
+<acl>
+    <page-openvpn-client>
+        <name>VPN: OpenVPN: Client</name>
+        <patterns>
+            <pattern>vpn_openvpn_client.php*</pattern>
+        </patterns>
+    </page-openvpn-client>
+    <page-openvpn-server>
+        <name>VPN: OpenVPN: Server</name>
+        <patterns>
+            <pattern>vpn_openvpn_server.php*</pattern>
+        </patterns>
+    </page-openvpn-server>
+</acl>

security/openvpn-legacy/src/opnsense/mvc/app/models/OPNsense/OpenVPN/Menu/Menu.xml

@@ -0,0 +1,12 @@
+<menu>
+    <VPN>
+        <OpenVPN>
+            <Servers VisibleName="Servers [legacy]" order="20" url="/vpn_openvpn_server.php">
+                <Edit url="/vpn_openvpn_server.php?*" visibility="hidden"/>
+            </Servers>
+            <Clients VisibleName="Clients [legacy]" order="22" url="/vpn_openvpn_client.php">
+                <Edit url="/vpn_openvpn_client.php?*" visibility="hidden"/>
+            </Clients>
+        </OpenVPN>
+    </VPN>
+</menu>