[FL-1884] GPIO application (#732)

* gpio: rename gpio application
* bq25896: add reading OTG config
* furi-hal-power: add is_otg_enabled API
* gpio: introduce new GPIO app, add OTG enable / disable
* variable-item-list: add enter callback
* gpio: add output test view and scene
* gpio app: fix GpioItemTester -> GpioItemTest

Co-authored-by: あく <alleteam@gmail.com>

lib/drivers/bq25896.h

@@ -18,6 +18,9 @@ void bq25896_enable_otg();
 /** Disable otg */
 void bq25896_disable_otg();
 
+/** Is otg enabled */
+bool bq25896_is_otg_enabled();
+
 /** Get VBUS Voltage in mV */
 uint16_t bq25896_get_vbus_voltage();