secure_boot: Secure Boot V2 verify app signature on update (without Secure boot)

- ESP32 ECO3, ESP32-S2/C3/S3

components/bootloader_support/include/esp_image_format.h

@@ -106,6 +106,20 @@ _Static_assert(sizeof(rtc_retain_mem_t) <= ESP_BOOTLOADER_RESERVE_RTC, "Reserved
  */
 esp_err_t esp_image_verify(esp_image_load_mode_t mode, const esp_partition_pos_t *part, esp_image_metadata_t *data);
 
+/**
+ * @brief Get metadata of app
+ *
+ * If encryption is enabled, data will be transparently decrypted.
+ *
+ * @param part Partition to load the app from.
+ * @param[out] metadata Pointer to the image metadata structure which is be filled in by this function.
+ *                      Fields will all be initialised by this function.
+ *
+ * @return
+ * - ESP_OK if filling of metadata was successful
+ */
+esp_err_t esp_image_get_metadata(const esp_partition_pos_t *part, esp_image_metadata_t *metadata);
+
 /**
  * @brief Verify and load an app image (available only in space of bootloader).
  *