classes: bundle: add simple mechanism for adding extra artifacts to bundle
classes: bundle: add simple mechanism for adding extra artifacts to bundle

This introduces variables RAUC_BUNDLE_EXTRA_DEPENDS and
RAUC_BUNDLE_EXTRA_FILES.

With RAUC_BUNDLE_EXTRA_FILES one specifies a space-separated list of
artifacts that are first search in DEPLOY_DIR_IMAGE and then in WORKDIR.

This allows both to add artifact via SRC_URI as well as by grabbing the
generated files from other deploy recipes.

To ensure the artifacts are placed in the deploy dir before fetching
them bundle generation one must add their recipe's name to the
RAUC_BUNDLE_EXTRA_DEPENDS variable:

  RAUC_BUNDLE_EXTRA_DEPENDS += "recipe-name"

The dependency defaults to the do_deploy task. If something else is
required, than one can optionally do this with the recipe-deptask
notation:

  RAUC_BUNDLE_EXTRA_DEPENDS += "recipe-name:do_<taskname>"

Signed-off-by: Enrico Jorns <a2e5f936c390f36494e46e71bcfbe365bb1e8c49@pengutronix.de>

rauc/meta-rauc,rauc/meta-rauc,rauc/meta-rauc,rauc/meta-rauc