.gitlab-ci.yml: publish RAUC bundle to HawkBit

The HawkBit instance needs to be configured externally and reachable from the runner performing the publishing step. The location of the instance must be provided through environment variables compatible with hawkbitctl, namely HAWKBIT_{URL,USERNAME,PASSWORD}. HAWKBIT_TENANT is optional and untested.

The bundle is added as an artifact to a new software module named after the bundle, using bundle timestamp as the version. The module is then placed in a distribution named after the image (not the bundle), with the exact same version.

docs/ci/hidden-jobs/publish-rauc-bundle-to-hawkbit.rst

@@ -15,9 +15,9 @@ Usage Guide
 ===========
 
 The `.publish-rauc-bundle-to-hawkbit` job should be paired with the
-:doc:`build-rauc-bundle-job` using the `needs: ...` keyword, so that the bundle
-file is transferred as an artifact between the two jobs, and no other artifacts
-are needlessly copied.
+:doc:`build-rauc-bundle-job` using the `needs: ...` and `dependencies: ...`
+keywords, so that the bundle file is transferred as an artifact between the two
+jobs, and no other artifacts are needlessly copied.
 
 The following variables should be set in the job definition: