Adds serde_with as a dependency in order to serialize Descriptor::id as
bytes instead of as a sequence.
Enables cfg_eval feature to enable conditional usage of serde_with
behind the "serde" feature flag for the fido-common crate.
Relies on ciborium as a dependency because coset requires one of
ciborium's error types. It should be possible to remove this type's
dependence on ciborium.
Nick Zana