Clear redirect url of auth after login

Previously this was never cleared. Therefore even when you logged in
next time, you were still redirected to the url you accessed at some
point without being logged in.

IHP/AuthSupport/Controller/Sessions.hs

@@ -90,7 +90,7 @@ createSessionAction = do
                     user <- user
                             |> set #failedLoginAttempts 0
                             |> updateRecord
-                    redirectUrl <- getSession "IHP.LoginSupport.redirectAfterLogin"
+                    redirectUrl <- getSessionAndClear "IHP.LoginSupport.redirectAfterLogin"
                     redirectToPath (fromMaybe (afterLoginRedirectPath @record) redirectUrl)
                 else do
                     setErrorMessage "Incorrect Password"