Various type improvements in preparation for new configuration type

David Rungerequested to merge
feat/type_improvements into main

This adds OpenPgpUserId, OpenPgpUserIdList, OpenPgpVersion, CryptographicKeyContext and SigningKeySetup for a new configuration file setup, that encodes data about a signing key setups.

This also prepares various types for their use in configuration by deriving serde::{Deserialize,Serialize}, Hash, Eq and PartialEq.

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