T6934: Add preshared key for zabbix-agent monitoring service

- Allow configure preshared key for zabbix-agent
- Added op mode command for generatre random psk secret
- Removed duplicate xml definition for psk settings


Configure authentication mode:
```
# set service monitoring zabbix-agent authentication mode
Possible completions:
   pre-shared-secret    Use a pre-shared secret key
```

Configure PSK Settings:
```
# set service monitoring zabbix-agent authentication psk
Possible completions:
   id                   ID for authentication
   secret               pre-shared secret key

```

Generate Random PSK:
```
$ generate psk random
Possible completions:
  <Enter>               Execute the current command
  size                  Key size in bytes

```

1 files changed, 17 insertions, 0 deletions

diff --git a/interface-definitions/service_monitoring_zabbix-agent.xml.in b/interface-definitions/service_monitoring_zabbix-agent.xml.in
index e44b31312..122e61e8b 100644
--- a/interface-definitions/service_monitoring_zabbix-agent.xml.in
+++ b/interface-definitions/service_monitoring_zabbix-agent.xml.in
@@ -10,6 +10,23 @@
               <priority>1280</priority>
             </properties>
             <children>
+              <node name="authentication">
+                <properties>
+                  <help>Authentication</help>
+                </properties>
+                <children>
+                  #include <include/auth-mode-pre-shared-secret.xml.i>
+                  <node name="psk">
+                    <properties>
+                      <help>Pre-shared key</help>
+                    </properties>
+                    <children>
+                      #include <include/auth-psk-id.xml.i>
+                      #include <include/auth-psk-secret.xml.i>
+                    </children>
+                  </node>
+                </children>
+              </node>
               <leafNode name="directory">
                 <properties>
                   <help>Folder containing individual Zabbix-agent configuration files</help>