doc: extensions: add doxyrunner
doc: extensions: add doxyrunner

zephyr.doxyrunner Sphinx extension is meant to replace multiple Python
and CMake scripts into a single Sphinx extension.

Signed-off-by: Gerard Marull-Paretas <bedb45f43a286e49f4dcda039a436b216ae61ef3@nordicsemi.no>

finikorg/zephyr,finikorg/zephyr,zephyrproject-rtos/zephyr,galak/zephyr,zephyrproject-rtos/zephyr,zephyrproject-rtos/zephyr,galak/zephyr,finikorg/zephyr,galak/zephyr,galak/zephyr,finikorg/zephyr,zephyrproject-rtos/zephyr,zephyrproject-rtos/zephyr,finikorg/zephyr,galak/zephyr