Add credentials into network-topology-rpcs

We have lost credential from netconf-node-fields in:
https://git.opendaylight.org/gerrit/c/netconf/+/109035

Add them into network-topology-rpcs.

JIRA: LIGHTY-284
Signed-off-by: Ivan Hrasko <ivan.hrasko@pantheon.tech>
Signed-off-by: tobias.pobocik <tobias.pobocik@pantheon.tech>
(cherry picked from commit c274e80)

Author: ihrasko

examples/devices/lighty-network-topology-device/src/test/resources/add_node_rpc_request.xml

@@ -5,8 +5,10 @@
             <node-id>test-nettopo-node</node-id>
             <host>127.0.0.1</host>
             <port>17835</port>
-            <username>admin</username>
-            <password>admin</password>
+            <login-password-unencrypted>
+                <username>admin</username>
+                <password>admin</password>
+            </login-password-unencrypted>
             <tcp-only>false</tcp-only>
             <keepalive-delay>0</keepalive-delay>
             <schemaless>false</schemaless>

examples/models/lighty-example-network-topology-device-model/src/main/yang/network-topology-rpcs@2024-02-02.yang

@@ -35,6 +35,7 @@ module network-topology-rpcs {
           key "node-id";
           uses nt:node-attributes;
           uses nnt:netconf-node-fields;
+          uses ond:credentials;
           uses ond:connection-oper;
           must "boolean(../underlay-topology[*]/node[./supporting-nodes/node-ref])";
               // This constraint is meant to ensure that a referenced node is in fact