This change add support for targeting a VNC server via a local UNIX
socket. It introduces a new `-target` CLI flag able to handle both TCP
"address:port" and "/path/to/unix.socket" formats, and deprecates the
previous `-targHost` and `-targPort` flags for future removal.
This change fixes a bug in the proxy session recording management, where
the proxy would record sessions even if the user didn't provide a value
for the `-recDir` CLI flag.
