There is no need for such a switch, the ESC's will work fine without it.

The only problem with LiPo is that they do not like an under voltage so you have to stop on time to be sure the battery is not drained too low. You can get a LiPo alarm, this is a small buzzer you can connect to the balance plug of the battery and monitors the battery voltage. The buzzer can produce over 80dB noise when its alarm goes off.

I know in the early days of LiPo batteries there was a kind of failsafe you connect between the receiver and the ESC and connected 2 wires to the battery which couls switch off the ESC at low voltage.