Implement /proc/sys/net/ipv4/ip_local_port_range

Speeds up the socket stress tests by a couple orders of magnitude.

PiperOrigin-RevId: 361721050

pkg/sentry/socket/netstack/stack.go

@@ -478,3 +478,13 @@ func (s *Stack) SetForwarding(protocol tcpip.NetworkProtocolNumber, enable bool)
 	}
 	return nil
 }
+
+// PortRange implements inet.Stack.PortRange.
+func (s *Stack) PortRange() (uint16, uint16) {
+	return s.Stack.PortRange()
+}
+
+// SetPortRange implements inet.Stack.SetPortRange.
+func (s *Stack) SetPortRange(start uint16, end uint16) error {
+	return syserr.TranslateNetstackError(s.Stack.SetPortRange(start, end)).ToError()
+}