tor-hsclient, arti-client, tor-keymgr, tor-netdoc: Use a keypair instead of StaticSecret.
Previously, when retrieving KS_hsc_desc_enc
keys (or any other x25519
keys) from the keystore, the keymgr would discard the public part of the
key (SSH private keys contain the public part of the key too). Instead
of discarding the public key and returning just the StaticSecret
, the
keymgr now returns a StaticKeypair
. This makes the x25519
EncodableKey
/ToEncodableKey
implementation consistent with the
ed25519 one (which retrieves key pairs rather than "unescorted"
secrets).