Only enable PINIOBOX task when needed

Previously the task was always enabled and there's no reason for it to be running if there are no boxID associations.

Saves a few cycles by not running. But has a bigger effect on the scheduler by minimizing the number of active tasks when possible.

src/test/unit/rc_controls_unittest.cc

@@ -655,4 +655,5 @@ void resetTryingToArm(void) {}
 void setLedProfile(uint8_t profile) { UNUSED(profile); }
 uint8_t getLedProfile(void) { return 0; }
 void compassStartCalibration(void) {}
+void pinioBoxTaskControl(void) {}
 }