This updates the minimal supported version of CMake to 3.16, which in turn enables us to use more CMake features and have a cleaner build system.
This is the version that provides most new features and also the one we use in our latest docker image for CI.
* make the project CMakelists to flash the external partition "pre_prov"
* Remove the dependancy of configure_ds.py on esptool.py
* Updated README
* Fix the help menu