Adds esp_mqtt_cxx component

- Component moved from esp-idf
- Files moved to adjust to esp-protocol structure

components/esp_mqtt_cxx/examples/tcp/CMakeLists.txt

@@ -0,0 +1,12 @@
+# The following four lines of boilerplate have to be in your project's CMakeLists
+# in this exact order for cmake to work correctly
+cmake_minimum_required(VERSION 3.16)
+
+# (Not part of the boilerplate)
+# This example uses an extra component for common functions such as Wi-Fi and Ethernet connection.
+# The path to esp_mqtt_cxx is also added.
+set(EXTRA_COMPONENT_DIRS
+    "../../../../common_components/protocol_examples_common" "../../")
+
+include($ENV{IDF_PATH}/tools/cmake/project.cmake)
+project(mqtt_tcp_cxx)