Update the list of people in groups B, C, and D of our revocation mechanism (2019 edition)

See https://tails.boum.org/doc/about/openpgp_keys/signing_key_revocation/index.en.html and internal.git:processes/signing_key_revocation.mdwn. We built this list in 2017 and I think it needs an update.

We should also create another ticket to update it again in some years.

Original created by @sajolida on 16665 (Redmine)

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