Reduce ID length for new credentials

This patch implements the following changes to reduce the ID length for
new credentials:
- Rename the old Credential type to FullCredential and introduce a
  StrippedCredential type and a Credential enum to differentiate between
  full and reduced credential data.
- Flatten the credential data to reduce encoding overhead.
- Remove the RP id from the credential data to reduce the total length.
- Add a marker field use_short_id to FullCredential so that we don’t
  change the credential ID for existing RKs.

Fixes: #29

CHANGELOG.md

@@ -13,12 +13,14 @@ and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0
 - Reject `rk` option in getAssertion ([#31][])
 - Ignore user data with empty ID in getAssertion ([#32][])
 - Allow three instead of two PIN retries per boot ([#35][])
+- Reduce ID length for new credentials ([#37][])
 
 [#26]: https://github.com/solokeys/fido-authenticator/issues/26
 [#28]: https://github.com/solokeys/fido-authenticator/issues/28
 [#31]: https://github.com/solokeys/fido-authenticator/issues/31
 [#32]: https://github.com/solokeys/fido-authenticator/issues/32
 [#35]: https://github.com/solokeys/fido-authenticator/issues/35
+[#37]: https://github.com/solokeys/fido-authenticator/issues/37
 
 ## [0.1.1] - 2022-08-22
 - Fix bug that treated U2F payloads as APDU over APDU in NFC transport @conorpp

Cargo.toml

@@ -39,6 +39,7 @@ log-error = []
 [dev-dependencies]
 # quickcheck = "1"
 rand = "0.8.4"
+trussed = { version = "0.1", features = ["virt"] }
 
 [package.metadata.docs.rs]
 features = ["dispatch"]