add compile_commands.json for cyd build

.gitignore

 .pio
+.cache

compile_commands.json

+.pio/build/cyd/compile_commands.json

extra_script.py

+import os
+Import("env")
+
+# include toolchain paths
+env.Replace(COMPILATIONDB_INCLUDE_TOOLCHAIN=True)
+
+# override compilation DB path
+env.Replace(COMPILATIONDB_PATH=os.path.join("$BUILD_DIR", "compile_commands.json"))

platformio.ini

 upload_port = /dev/ttyUSB1
 monitor_port = /dev/ttyUSB1
 monitor_speed = 115200
+extra_scripts = pre:extra_script.py
 build_flags =
   -DSENSOR_HOSTNAME_PREFIX=\"cyd-\"
   "-DNAME_OF_FEATURE=\"Remote Control\""