Resolve "Update copyright year in headers"
This MR deletes the outdated scripts used for managing copyright headers and provides a new one in
scripts/maintainer-tools/copyright-headers. Also, similarly to before, it also provides a Dockerfile for a
gekkofs/copyright-header image that encapsulates a version of Osterman's copyright-header Gem appropriately patched for our needs. Please refer to the README.md file in
scripts/maintainer-tools/copyright-headers for more details.
Closes #142 (closed)