Add licensing and copyright information for all files in this repository. This
either happens in the file itself as a comment header or in the file
`.reuse/dep5`.
This commit also adds a Github workflow to check pull requests and adapts
copyright.pl to the changes.
Closes#8869
Added test 971 to verify that the list is in sync with the files in
cmdline-opts. The check also verifies that .d-files that uses Added:
specify the same version number as the options-in-versions file does.
Closes#5381
