Add Unknown to enum since optional isn't working with candid as expected

Author: sea-snake

src/internet_identity/src/openid.rs

@@ -222,6 +222,7 @@ impl OpenIdCredential {
             let verification_scheme = provider.email_verification_scheme()?;
 
             match verification_scheme {
+                Unknown => None,
                 Google => self.get_google_verified_email(),
                 Microsoft => self.get_microsoft_verified_email(),
             }

src/internet_identity_interface/src/internet_identity/types.rs

@@ -393,6 +393,7 @@ pub enum DeployArchiveResult {
 
 #[derive(Clone, Copy, Debug, CandidType, Serialize, Deserialize, Eq, PartialEq)]
 pub enum OpenIdEmailVerificationScheme {
+    Unknown,
     Google,
     Microsoft,
 }