commander: changes when USB connected

- skip avionics rail voltage check when USB connected
 - skip forced reboot on USB disconnect if circuit breaker set
 - avionics voltage preflight check don't silently fail if system_power unavailble
     - explicitly set supply check circuit breaker (CBRK_SUPPLY_CHK)

posix-configs/eagle/hil/mainapphil.config

@@ -2,6 +2,7 @@ uorb start
 muorb start
 # Wait 1s before setting parameters for muorb to initialize
 sleep 1
+param set CBRK_SUPPLY_CHK 894281
 param set MAV_BROADCAST 1
 mavlink start -x -u 14556
 sleep 1

posix-configs/eagle/hil/px4.config

@@ -1,6 +1,7 @@
 uorb start
 qshell start
 
+param set CBRK_SUPPLY_CHK 894281
 param set SYS_AUTOSTART 4001
 param set SYS_AUTOCONFIG 1
 param set MAV_TYPE 2