Test rest api of functions, sink and source in /api/v2 and /api/v3

/api/v2 and /api/v3
source
```
./bin/pulsar-admin source list --namespace default --tenant public
[]
curl http://localhost:8080/admin/v3/source/public/default ok
curl http://localhost:8080/admin/v2/source/public/default

Error 404 Not Found

HTTP ERROR 404

Problem accessing /admin/v2/source/public/default/. Reason:

    Not Found

```
function
```
./bin/pulsar-admin functions stats --tenant public --namespace default --name reverse2
{
"receivedTotal" : 0,
"processedSuccessfullyTotal" : 0,
"systemExceptionsTotal" : 0,
"userExceptionsTotal" : 0,
"avgProcessLatency" : null,
"1min" : {
"receivedTotal" : 0,
"processedSuccessfullyTotal" : 0,
"systemExceptionsTotal" : 0,
"userExceptionsTotal" : 0,
"avgProcessLatency" : null
},
"lastInvocation" : null,
"instances" : [ {
"instanceId" : 0,
"metrics" : {
"receivedTotal" : 0,
"processedSuccessfullyTotal" : 0,
"systemExceptionsTotal" : 0,
"userExceptionsTotal" : 0,
"avgProcessLatency" : null,
"1min" : {
"receivedTotal" : 0,
"processedSuccessfullyTotal" : 0,
"systemExceptionsTotal" : 0,
"userExceptionsTotal" : 0,
"avgProcessLatency" : null
},
"lastInvocation" : null,
"userMetrics" : { }
}
} ]
}
curl http://localhost:8080/admin/v3/functions/public/default/reverse2/stats ok
curl http://localhost:8080/admin/v2/functions/public/default/reverse2/stats

Error 404 Not Found

HTTP ERROR 404

Problem accessing /admin/v2/functions/public/default/reverse2/stats. Reason:

    Not Found

```

```
curl -X POST http://localhost:8080/admin/v2/functions/public/default/reverse2/0/start 404
curl -X POST http://localhost:8080/admin/v3/functions/public/default/reverse2/0/start ok
```

sink
```
./bin/pulsar-admin sink list --namespace default --tenant public
[]
curl http://localhost:8080/admin/v3/sink/public/default ok
curl http://localhost:8080/admin/v2/sink/public/default 404
```