[esp] Add ESP-IDF cmake example.

esp/cpp/04_esp-idf-arduino/CMakeLists.txt

@@ -0,0 +1,18 @@
+# For more information about build system see
+# https://docs.espressif.com/projects/esp-idf/en/latest/api-guides/build-system.html
+# The following five lines of boilerplate have to be in your project's
+# CMakeLists in this exact order for cmake to work correctly
+cmake_minimum_required(VERSION 3.26)
+
+include($ENV{IDF_PATH}/tools/cmake/project.cmake)
+
+project(
+    #[[NAME]]   esp-idf-arduino
+    VERSION     0.1
+    DESCRIPTION "Example ESP-IDF cmake project"
+    LANGUAGES   CXX
+)
+
+# For writing pure cmake components, see the documentation
+# https://docs.espressif.com/projects/esp-idf/en/stable/esp32/api-guides/build-system.html#writing-pure-cmake-components
+idf_build_set_property(COMPILE_OPTIONS "-Wno-error" APPEND)