Move the existing CMake and build functionality from the west repository
to zephyr. The rationale behind this move is that it's very tightly
coupled with the Zephyr build system and is only used by the extension
commands implemented in the zephyr tree.
If additional extension commands in third-party repos want to use the
functionality they can add $ZEPHYR_BASE/scripts/west_commands to the
Python system path.
The implmentations in the west repo will be deprecated.
Signed-off-by: Carles Cufi <carles.cufi@nordicsemi.no>
