Add keypair & update pubkey

Keypair & FullKeypair match structs in damus ios

Signed-off-by: kernelkind <kernelkind@gmail.com>
Signed-off-by: William Casarin <jb55@jb55.com>

enostr/src/error.rs

@@ -8,8 +8,10 @@ pub enum Error {
     Empty,
     DecodeFailed,
     HexDecodeFailed,
+    InvalidBech32,
     InvalidByteSize,
     InvalidSignature,
+    InvalidPublicKey,
     // Secp(secp256k1::Error),
     Json(serde_json::Error),
     Generic(String),
@@ -23,6 +25,7 @@ impl std::cmp::PartialEq for Error {
             (Error::HexDecodeFailed, Error::HexDecodeFailed) => true,
             (Error::InvalidSignature, Error::InvalidSignature) => true,
             (Error::InvalidByteSize, Error::InvalidByteSize) => true,
+            (Error::InvalidPublicKey, Error::InvalidPublicKey) => true,
             // This is slightly wrong but whatevs
             (Error::Json(..), Error::Json(..)) => true,
             (Error::Generic(left), Error::Generic(right)) => left == right,
@@ -40,6 +43,8 @@ impl fmt::Display for Error {
             Self::InvalidSignature => write!(f, "invalid signature"),
             Self::HexDecodeFailed => write!(f, "hex decoding failed"),
             Self::InvalidByteSize => write!(f, "invalid byte size"),
+            Self::InvalidBech32 => write!(f, "invalid bech32 string"),
+            Self::InvalidPublicKey => write!(f, "invalid public key"),
             //Self::Secp(e) => write!(f, "{e}"),
             Self::Json(e) => write!(f, "{e}"),
             Self::Generic(e) => write!(f, "{e}"),