sd detect pin feature (#222)

* test sd detect pin
* sd detect support for f2 board

firmware/targets/f2/api-hal/api-hal-gpio.c

@@ -12,3 +12,7 @@ void hal_gpio_init(GpioPin* gpio, GpioMode mode, GpioPull pull, GpioSpeed speed)
 
     HAL_GPIO_Init(gpio->port, &GPIO_InitStruct);
 }
+
+bool hal_gpio_read_sd_detect(void) {
+    return true;
+}

firmware/targets/f2/api-hal/api-hal-gpio.h

@@ -58,4 +58,6 @@ static inline bool hal_gpio_read(const GpioPin* gpio) {
     } else {
         return false;
     }
-}
+}
+
+bool hal_gpio_read_sd_detect(void);