Move OPAQUE into Iota and harden password authentication

iota-opaque/src/opaque/error.rs

@@ -0,0 +1,15 @@
+#[derive(Debug, thiserror::Error)]
+pub enum OpaqueIntegrationError {
+    #[error("invalid OPAQUE exchange: {0}")]
+    Opaque(String),
+    #[error("OPAQUE context field is too large")]
+    FieldTooLarge,
+}
+
+#[derive(Debug, thiserror::Error)]
+pub enum LoginFinishError {
+    #[error("invalid OPAQUE finalization message")]
+    InvalidMessage,
+    #[error("OPAQUE authentication failed")]
+    AuthenticationFailed,
+}