Verify the main app mostly sleeps

This validates that the main watch app spends at
least 99.5% of it's time sleeping in the first 10
seconds.

firmware/Test/Common/TestBoard.h

@@ -30,3 +30,4 @@ void board_init();
 extern BSP::Schedule::LowPowerTaskScheduler<10> g_sched;
 extern BSP::GpioDriver g_gpioa;
 extern BSP::UsartDriver g_test_uart;
+extern BSP::GpioPin g_debug0_pin;