sysbuild_root

Convert Zephyr roots to absolute paths to be used by sysbuild.

This module converts all relative paths in the following root lists to absolute paths, relative from APP_DIR:

• ARCH_ROOT

• BOARD_ROOT

• MODULE_EXT_ROOT

• SCA_ROOT

• SNIPPET_ROOT

• SOC_ROOT

If a root is defined, this module checks the list of paths in the root, converts any relative path to an absolute path, and updates the root list. If a root is undefined, it is still undefined once this module has loaded.

Converted paths are placed in the CMake cache so that they are propagated correctly to image builds.