MQTT: Integrate esp-mqtt library into idf

added docs and tests for mqtt library, small fixes (removed warnings, option for custom outbox, websocket bug fixed for longer transports). refactored to use common tcp_transport component, support for CMake build system.
Closes #2108

components/esp_http_client/lib/include/http_utils.h

@@ -16,6 +16,7 @@
 #ifndef _HTTP_UTILS_H_
 #define _HTTP_UTILS_H_
 #include <sys/time.h>
+#include "transport_utils.h"
 /**
  * @brief      Assign new_str to *str pointer, and realloc *str if it not NULL
  *
@@ -78,18 +79,8 @@ char *http_utils_join_string(const char *first_str, int len_first, const char *s
  */
 int http_utils_str_starts_with(const char *str, const char *start);
 
-/**
- * @brief      Convert milliseconds to timeval struct
- *
- * @param[in]  timeout_ms  The timeout milliseconds
- * @param[out] tv          Timeval struct
- */
-void http_utils_ms_to_timeval(int timeout_ms, struct timeval *tv);
 
-#define HTTP_MEM_CHECK(TAG, a, action) if (!(a)) {                                                      \
-        ESP_LOGE(TAG,"%s:%d (%s): %s", __FILE__, __LINE__, __FUNCTION__, "Memory exhausted");       \
-        action;                                                                                         \
-        }
+#define HTTP_MEM_CHECK(TAG, a, action) TRANSPORT_MEM_CHECK(TAG, a, action)
 
 
 #endif