esp_vfs_fat_sdcard_format_cfg() function

- ESP_OK - ESP_ERR_INVALID_STATE: FAT partition isn't mounted, call esp_vfs_fat_sdmmc_mount or esp_vfs_fat_sdspi_mount first - ESP_ERR_NO_MEM: if memory can not be allocated - ESP_FAIL: fail to format it, or fail to mount back

This API should be only called when the FAT is already mounted.