Add APP_DIR as a kconfig environment variable.
This is useful in cases where you want to set a config path relative to
the directory of the application.
An example of this is how many sysbuild.cmake files sets the source
directory like this:
ExternalZephyrProject_Add(
APPLICATION remote
SOURCE_DIR ${APP_DIR}/remote
BOARD ${SB_CONFIG_REMOTE_BOARD}
)
The same however cannot be done in Kconfig.sysbuild:
config NETCORE_IMAGE_PATH
default "${APP_DIR}/<image_path>" if NETCORE_ABC
Instead they must use ZEPHYR_MY_MODULE_MODULE_DIR, however not all
applications are part of a zephyr module.
Signed-off-by: Joakim Andersson <joerchan@gmail.com>
12fdde6694