Fix FORWARD session host handling in SAM and refactor SAMSocket::ProcessStreamForward

[nobs2p]

• Fixed validation of HOST and PORT parameters for FORWARD sessions:
  • Improved IP address parsing with fallback to 127.0.0.1 if invalid
• Added checks for required parameters (ID, HOST, PORT)
• General cleanup and refactoring for improved readability and stability

[Vort]

Added checks for required parameters (ID, HOST, PORT)

The thing is HOST is actually not required.
Note square brackets here: [HOST=$host].
Following text also confirms this:

$host is the hostname or IP address of the socket server to which SAM will forward connection requests. If not given, SAM takes the IP of the socket that issued the forward command.