SignInSso: return to server list on Cancel click

TODO.md

@@ -1,7 +1,6 @@
 # TODO
 
 - server list sorting method / explain what the % number is (stability)
-- clicking cancel on SSO "waiting" box doesn't do anything the first time
 - spam alt+shift+a when starting app on server browser → segfault
 - remove items.Device
 - register tab for sso servers?

src/gui/Pages/AddAccount/SignInSso.qml

@@ -26,6 +26,15 @@ SignInBase {
         })
     }
 
+    function cancel() {
+        if (loginFuture) {
+            page.loginFuture.cancel()
+            page.loginFuture = null
+        }
+
+        page.exitRequested()
+    }
+
 
     applyButton.text: qsTr("Waiting")
     applyButton.loading: true