Export AuthProviders, DefaultProviderSettings and ProviderSettingsItem (#3249)

`Settings` allows to pass `providerSettings`, but right now there isn't a way to constuct them out of the existing components as they aren't exported.

.changeset/moody-pugs-smoke.md

@@ -0,0 +1,5 @@
+---
+'@backstage/plugin-user-settings': patch
+---
+
+Export `AuthProviders`, `DefaultProviderSettings` and `ProviderSettingsItem`.

plugins/user-settings/src/components/AuthProviders/index.ts

@@ -16,3 +16,4 @@
 
 export { AuthProviders } from './AuthProviders';
 export { DefaultProviderSettings } from './DefaultProviderSettings';
+export { ProviderSettingsItem } from './ProviderSettingsItem';

plugins/user-settings/src/components/index.ts

@@ -0,0 +1,18 @@
+/*
+ * Copyright 2020 Spotify AB
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *     http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+export { Settings } from './Settings';
+export { SettingsPage as Router } from './SettingsPage';
+export * from './AuthProviders';

plugins/user-settings/src/index.ts

@@ -14,5 +14,4 @@
  * limitations under the License.
  */
 export { plugin } from './plugin';
-export { Settings } from './components/Settings';
-export { SettingsPage as Router } from './components/SettingsPage';
+export * from './components/';