rpc: adjust script creation with empty parameters list
Always use NEWARRAY0 where possible, see
26d04a642a/src/neo/VM/Helper.cs (L41).
Compatibility is tested:
```
anna@kiwi:~/Documents/GitProjects/nspcc-dev/neo-go$ curl -d '{ "jsonrpc": "2.0", "id": 1, "method": "invokefunction", "params": ["50befd26fdf6e4d957c11e078b24ebce6291456f", "a", [] ]}' seed1.neo.org:10332 | json_pp
% Total % Received % Xferd Average Speed Time Time Time Current
Dload Upload Total Spent Left Speed
100 370 0 248 100 122 127 62 0:00:01 0:00:01 --:--:-- 190
{
"result" : {
"notifications" : [],
"stack" : [],
"script" : "wh8MAWEMFG9FkWLO6ySLBx7BV9nk9v0m/b5QQWJ9W1I=",
"gasconsumed" : "98403",
"state" : "FAULT",
"exception" : "Called Contract Does Not Exist: 0x50befd26fdf6e4d957c11e078b24ebce6291456f"
},
"jsonrpc" : "2.0",
"id" : 1
}
```
aa3a5fc492