Move optional modules to a submanifest and make them optional by
default.
This is just a POC, might require some more thought. The idea is to look
at the optional manifest as an area for modules that work with Zephyr,
but not needed directly by zephyr. This could be documented somewhere
for discovery purposes allowing users to enable such modules in their
downstream if desired.
See #54276
Signed-off-by: Anas Nashif <anas.nashif@intel.com>
Import any manifest files in a new 'submanifests' directory into
west.yml.
This lets users define custom zephyr modules or easily override
built-in modules by dropping their own manifest files into
submanifests/some-user-file.yaml.
Provide an example and a README with links to the relevant
documentation in 'submanifests' to get users started.
Signed-off-by: Martí Bolívar <marti.bolivar@nordicsemi.no>