This commit marks all functions in interrupt_controller_hal.h, cpu_ll.h and cpu_hal.h as deprecated.
Users should use functions from esp_cpu.h instead.
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.
The legacy driver is still available, but new feature won't be added.
Enable RMT_SUPPRESS_DEPRECATE_WARN if you don't want to see the
deprecated warnings.
