feat(esp_http_client): SHA256 support in digest auth

Added support for using SHA256 algorithm while calculating
digest auth in HTTP client connection

Closes https://github.com/espressif/esp-idf/issues/12383

components/esp_http_client/lib/include/http_utils.h

@@ -55,6 +55,17 @@ void http_utils_trim_whitespace(char **str);
  */
 char *http_utils_get_string_between(const char *str, const char *begin, const char *end);
 
+/**
+ * @brief      Returns a string that contains the part after the search string till the end of the source string.
+ *             It will allocate a new memory space for this string, so you need to free it when no longer used
+ *
+ * @param[in]  str    The source string
+ * @param[in]  begin  The search string
+ *
+ * @return     The string between begin and the end of str
+ */
+char *http_utils_get_string_after(const char *str, const char *begin);
+
 /**
  * @brief      Join 2 strings to one
  *             It will allocate a new memory space for this string, so you need to free it when no longer use