WIP: Scripts: add script to check copyrights

Context

This MR adds a script which looks at the Git history and checks that the copyrights in the source files reflect this Git history. For instance, if a commit dated from 2020 and authored by someone@nomadic-labs.com modifies file src/bin_node/node_config_file.ml, this file should have Copyright 2020 Nomadic Labs.

Currently the copyrights are not up-to-date and this script should help to fix that.

This script can also be invoked with the --update option to update licenses in place.

This script can also be invoked with -w to get a warning if there is no rule to deduce the expected copyright author from a commit author e-mail address. This should help get exhaustive rules but we need to decide whether we are ok with having a list of e-mail addresses in the sources (for some, we can just match on the domain, but some developers have e-mail addresses for which we would need to store the full e-mail address).

I did not check the output of the script very extensively yet.

Manually testing the MR

Check copyrights for all .ml and .mli files (will not modify your files):

dune exec scripts/copyright/main.exe -- $(find src -name '*.ml') $(find src -name '*.mli')

Update copyrights for all .ml and .mli files (careful: this will modify files):

dune exec scripts/copyright/main.exe -- $(find src -name '*.ml') $(find src -name '*.mli') --update

(you can also use find src -name '*.ml' -or -name '*.mli' but apparently that's not POSIX)

Checklist

• Provide automatic testing (see the testing guide).
• Add item in the Development Version section of CHANGES.md (only for new features and bug fixes).

Reviewers

@adrianbrink @pirbo