Dead code warnings

There are some dead code warnings from cargo doc --locked --workspace --all-features --document-private-items that I can't immediately resolve:

• In tor-dirmgr, the Store trait's methods delete_consensus and delete_bridgedesc. Is expiry handled separately? If so the lack of calls may be fine. We probably don't want to delete these methods since they seem sensible for completeness, so if the code is fine, we should remove the TODO from the allows.

• In tor-proto::circuit, WindowParams has a maximum method which is never called. This probably means the code is wrong.

• In tor-proto::crypto, the RelayCrypt trait and ServerHandshake::server are both unused. I don't understand this.

I'm making an MR to allow the tree to build cleanly, in which I will make allows for these. But they should be investigated.

@nickm, I think you may know the answers?