In order to bring consistency in-tree, migrate all subsystems code to
the new prefix <zephyr/...>. Note that the conversion has been scripted,
refer to zephyrproject-rtos#45388 for more details.
Signed-off-by: Gerard Marull-Paretas <gerard.marull@nordicsemi.no>
Stats are an optional feature, moving it into a separate source file
improves code readability.
Signed-off-by: Gerard Marull-Paretas <gerard.marull@nordicsemi.no>