kconfig: add dt_path_enabled, dt_alias_enabled
kconfig: add dt_path_enabled, dt_alias_enabled

There is already a way to check if a node is enabled based on its node
label, but we don't have an equivalent way to do that for a path or an
alias. Add them. These rely on the same underlying edtlib machinery to
get their jobs done, but are being treated differently within Kconfig
in order to match distinctions between paths and aliases made in the
devicetree.h API.

Signed-off-by: Martí Bolívar <9d90ac4c7bf6a305f6bfd81a23c7859bc883380e@nordicsemi.no>

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