Make it easier to look up error messages

tools/gen_esp_err_to_name.py generates
components/esp32/esp_err_to_name.c for lookup of the error codes from
all of the IDF project and easily identify all codes in one place

components/esp32/include/esp_err.h

@@ -42,6 +42,39 @@ typedef int32_t esp_err_t;
 
 #define ESP_ERR_WIFI_BASE       0x3000 /*!< Starting number of WiFi error codes */
 
+/**
+  * @brief Returns string for esp_err_t error codes
+  *
+  * This function finds the error code in a pre-generated lookup-table and
+  * returns its string representation.
+  *
+  * The function is generated by the Python script
+  * tools/gen_esp_err_to_name.py which should be run each time an esp_err_t
+  * error is modified, created or removed from the IDF project.
+  *
+  * @param code esp_err_t error code
+  * @return string error message
+  */
+const char *esp_err_to_name(esp_err_t code);
+
+/**
+  * @brief Returns string for esp_err_t and system error codes
+  *
+  * This function finds the error code in a pre-generated lookup-table of
+  * esp_err_t errors and returns its string representation. If the error code
+  * is not found then it is attempted to be found among system errors.
+  *
+  * The function is generated by the Python script
+  * tools/gen_esp_err_to_name.py which should be run each time an esp_err_t
+  * error is modified, created or removed from the IDF project.
+  *
+  * @param code esp_err_t error code
+  * @param[out] buf buffer where the error message should be written
+  * @param buflen Size of buffer buf. At most buflen bytes are written into the buf buffer (including the terminating null byte).
+  * @return buf containing the string error message
+  */
+const char *esp_err_to_name_r(esp_err_t code, char *buf, size_t buflen);
+
 void _esp_error_check_failed(esp_err_t rc, const char *file, int line, const char *function, const char *expression) __attribute__((noreturn));
 
 #ifndef __ASSERT_FUNC