Revert "Inline USB start/stop callback tasks"

This reverts commit 01ed893.

Because starting file system within event loop failed:

```
ESP_ERROR_CHECK failed: esp_err_t 0x1 (ERROR) at 0x4037ab88
  #0  0x4037ab88 in _esp_error_check_failed at /home/runner/work/esp32-arduino-lib-builder/esp32-arduino-lib-builder/esp-idf/components/esp_system/esp_err.c:42

file: "lib/storage/storage.cpp" line 117
func: void switchToApplicationMode()
expression: FFat.begin()

abort() was called at PC 0x4037ab8b on core 1

Backtrace: 0x403777ba:0x3fcf2100 0x4037ab95:0x3fcf2120 0x4038058d:0x3fcf2140 0x4037ab8b:0x3fcf21c0 0x42002afb:0x3fcf21e0 0x42002b15:0x3fcf2200 0x4205e6d5:0x3fcf2220 0x4205e754:0x3fcf2270
  #0  0x403777ba in panic_abort at /home/runner/work/esp32-arduino-lib-builder/esp32-arduino-lib-builder/esp-idf/components/esp_system/panic.c:408
  #1  0x4037ab95 in esp_system_abort at /home/runner/work/esp32-arduino-lib-builder/esp32-arduino-lib-builder/esp-idf/components/esp_system/esp_system.c:137
  #2  0x4038058d in abort at /home/runner/work/esp32-arduino-lib-builder/esp32-arduino-lib-builder/esp-idf/components/newlib/abort.c:46
  #3  0x4037ab8b in _esp_error_check_failed at /home/runner/work/esp32-arduino-lib-builder/esp32-arduino-lib-builder/esp-idf/components/esp_system/esp_err.c:43
  #4  0x42002afb in switchToApplicationMode() at lib/storage/storage.cpp:117 (discriminator 1)
  #5  0x42002b15 in usbStoppedCallback(void*, char const*, int, void*) at lib/storage/storage.cpp:139
  #6  0x4205e6d5 in handler_execute at /home/runner/work/esp32-arduino-lib-builder/esp32-arduino-lib-builder/esp-idf/components/esp_event/esp_event.c:145
      (inlined by) esp_event_loop_run at /home/runner/work/esp32-arduino-lib-builder/esp32-arduino-lib-builder/esp-idf/components/esp_event/esp_event.c:598
  #7  0x4205e754 in esp_event_loop_run_task at /home/runner/work/esp32-arduino-lib-builder/esp32-arduino-lib-builder/esp-idf/components/esp_event/esp_event.c:115 (discriminator 15)
```

Author: dhebbeker

lib/storage/storage.cpp

@@ -128,6 +128,19 @@ static void switchToUSBMode()
     MSC.mediaPresent(true);
 }
 
+static void usb_stopped_cb(void *const pvParameters)
+{
+    switchToApplicationMode();
+    listFiles("/");
+    vTaskDelete(nullptr);
+}
+
+static void usb_started_cb(void *const pvParameters)
+{
+    switchToUSBMode();
+    vTaskDelete(nullptr);
+}
+
 static bool usbIsRunning = false;
 static void usbStoppedCallback(void *, esp_event_base_t, int32_t, void *)
 {
@@ -136,13 +149,12 @@ static void usbStoppedCallback(void *, esp_event_base_t, int32_t, void *)
         return;
     }
     usbIsRunning = false;
-    switchToApplicationMode();
+    xTaskCreate(usb_stopped_cb, "USB_Stopped_CB", 4096, nullptr, 5, nullptr);
 }
-
 static void usbStartedCallback(void *, esp_event_base_t, int32_t, void *)
 {
     usbIsRunning = true;
-    switchToUSBMode();
+    xTaskCreate(usb_started_cb, "USB_Started_CB", 4096, nullptr, 5, nullptr);
 }
 
 const esp_partition_t *check_ffat_partition(const char *label); // defined in FFat.cpp