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.
While using esp_wifi_set_config, flag pmf_capable defaults to 0.
Users may not bother to enable it, which prevents connection to a
WPA3 AP. Or the AP may reset into WPA3 mode failing the re-connection.
To ensure better security, deprecate the pmf_capable flag and set it to
true internally.
