Settings/Bind: Ask the user to validate the email again if they have not validated it yet

instead of displaying an error dialog.
This bug happened only with the new HS add and bind APIs (MSC2290) flow because new IS API returns only `M_UNKNOWN`.

Riot/Modules/Settings/Discovery/ThreePidDetails/SettingsDiscoveryThreePidDetailsViewModel.swift

@@ -190,7 +190,9 @@ final class SettingsDiscoveryThreePidDetailsViewModel: SettingsDiscoveryThreePid
 
                 self.checkThreePidDiscoverability()
             case .failure(let error):
-                if let mxError = MXError(nsError: error), mxError.errcode == kMXErrCodeStringThreePIDAuthFailed {
+                if let mxError = MXError(nsError: error),
+                    (mxError.errcode == kMXErrCodeStringThreePIDAuthFailed
+                        || mxError.errcode == kMXErrCodeStringUnknown) {
                     self.update(viewState: .loaded(displayMode: .pendingThreePidVerification))
                 } else {
                     if threePidAddSession.medium == kMX3PIDMediumEmail {