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.
For some of the MSPI high frequency setting (e.g. 80M DDR mode Flash or PSRAM), timing tuning is required.
Certain delays will be added to the MSPI RX direction. When system clock switches down, the delays should be
cleared. When system clock switches up, the delays should be restored.
