By importing `_time` in `freertos_sleep()`, the host time module was imported as `time` again as well, breaking all later code using e.g. `time.ticks_ms()`. Fix this by using `time` in `sys_kernel.freertos_sleep()` as well.
The functionality has been distributed to: - kernel (hardware_version, freertos_sleep) - uctx (scope) - sys_buttons (new, low-level button access) - sys_display (new, low-level display access)