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.
1. Move adding of prefix/postfix to the private key to example code.
This is to preserve forward compatibility when more curves are supported.
2. Documentation correction of bootstrapping key configuration.
1. Add Example for DPP Enrollee
2. Use DPP Supplicant API's to setup connection
3. Add support for multiple channels in Bootstrapping
4. Add Unity testcase for testing Offchannel operations
Closes https://github.com/espressif/esp-idf/issues/5654
