cmake: Build all examples in CI

Includes some fixes for compile errors/warnings in examples.

examples/bluetooth/ble_throughput/throughput_server/CMakeLists.txt

@@ -0,0 +1,10 @@
+# The following lines of boilerplate have to be in your project's
+# CMakeLists in this exact order for cmake to work correctly
+cmake_minimum_required(VERSION 3.5)
+
+set(MAIN_SRCS
+    main/example_ble_server_throughput.c
+    )
+
+include($ENV{IDF_PATH}/tools/cmake/project.cmake)
+project(throughput_server_demo)