Refactor COSE serialization and deserialization

This patch introduces the RawPublicKey helper type that takes care of
serialization and deserialization of the key type.  The *PublicKey
structs now only need to check if all required fields are present and
have the correct value.  It also adds extensive tests to make sure that
serialization and deserialization work correctly.

This patch is ported from: trussed-dev/ctap-types#8

Cargo.toml

@@ -8,7 +8,7 @@ categories = ["embedded", "encoding", "no-std"]
 keywords = ["cose", "cbor", "rust", "no-std"]
 repository = "https://github.com/ycrypto/cosey"
 readme = "README.md"
-edition = "2018"
+edition = "2021"
 
 [dependencies]
 heapless-bytes = "0.3.0"
@@ -18,3 +18,11 @@ serde_repr = "0.1"
 version = "1.0"
 default-features = false
 features = ["derive"]
+
+[dev-dependencies]
+cbor-smol = "0.4"
+ciborium = "0.2.1"
+hex = "0.4.3"
+itertools = "0.12.0"
+quickcheck = "1.0.3"
+serde = "1"