chore: add missing license information for code artefacts

[tom-rm-meyer-ISST]

Description

During Quality Gate I realized, that license headers have been missing for code artifacts.

Added these license files and provided a small script for sanity checks.

Notes:

• regression test has been conducted for safety reasons (beside helm install)
• will be used as new 2.1.0 basis
• Chart version not bumped as only license headers have been changed

Pre-review checks

Please ensure to do as many of the following checks as possible, before asking for committer review:

• DEPENDENCIES are up-to-date. Dash license tool. Committers can open IP issues for restricted libs.
• Copyright and license header are present on all affected files
• If helm chart has been changed, the chart version has been bumped to either next major, minor or patch level (compared to released chart).