modules: adding support for ROOTs definitions in zephyr/module.yml

Fixes: #25215

This commit introduces the possibility of defining ROOTs in a Zephyr
module and have it automatically appended to list of other ROOTs.
Supported with this commit:
- BOARD_ROOT
- SOC_ROOT
- DTS_ROOT
- ARCH_ROOT

In order to support this in Zephyr module files, the detection of west
has been moved to dedicated west.cmake file and included immediately
after python.cmake.

Also the inclusion of zephyr_modules.cmake has moved before first use
of BOARD_ROOT.

Signed-off-by: Torsten Rasmussen <Torsten.Rasmussen@nordicsemi.no>