provide option to pass Null as alternate key with pipe

[vnitinv]

Need the logical OR support for the key.

UTMStatusTable:
    rpc: show-utmd-status
    item:  //utmd-status
    view: UTMStatusView
    key: re-name | Null

UTMStatusView:
    fields:
        running: { running: flag }

We should be also able to support both item and key as logical OR operator

UTMStatusTable:
    rpc: show-utmd-status
    item: //multi-routing-engine-item/utmd-status | //utmd-status
    view: UTMStatusView
    key: 
      - re-name | Null

UTMStatusView:
    fields:
        running: { running: flag }

Note: When the item is using OR operator, key need to be passed as list (the way code handles it)

Standalone Output:

root@snpsrx4600h> show security utm status | display xml

<rpc-reply xmlns:junos="http://xml.juniper.net/junos/19.2R0/junos">
    <utmd-status xmlns="http://xml.juniper.net/junos/19.2R0/junos-utmd">
        <running/>
    </utmd-status>
    <cli>
        <banner></banner>
    </cli>
</rpc-reply>

In case of standalone, above table should return

{'running': True}

High-Availability Output:

root@riad-srx4200-4> show security utm status | display xml

<rpc-reply xmlns:junos="http://xml.juniper.net/junos/20.1I0/junos">
    <multi-routing-engine-results>
        
        <multi-routing-engine-item>
            
            <re-name>node0</re-name>
            
            <utmd-status xmlns="http://xml.juniper.net/junos/20.1I0/junos-utmd"><running/>
        </utmd-status>
    </multi-routing-engine-item>
    
    <multi-routing-engine-item>
        
        <re-name>node1</re-name>
        
        <utmd-status xmlns="http://xml.juniper.net/junos/20.1I0/junos-utmd"><running/>
    </utmd-status>
</multi-routing-engine-item>

    </multi-routing-engine-results>
    <cli>
<banner>{primary:node0}</banner>
    </cli>
</rpc-reply>

In case of cluster, above table/view should return

{'node0': {'running': True}, 'node1': {'running': True}}

[coveralls]

Coverage increased (+0.02%) to 94.981% when pulling e5a7374 on vnitinv:key-contains-Null into 51ca852 on Juniper:master.

[vnitinv]

ok to test

[vnitinv]

ok to test

[vnitinv]

retest this please

[dineshbaburam91]

Looks good