Start deep link page synchronously in SettingsActivity

- Use a synchronous API to make SettingsActivity start deep link intent
  in onCreate
- Change SettingsHomepageActivity from an alias to a real activity
- Clean up redundant codes

Fix: 206585572
Test: Manual, robotest build pass
Change-Id: Idf42c026f593bb5801a13cae250d1523030b7092

src/com/android/settings/homepage/DeepLinkHomepageActivity.java

@@ -0,0 +1,21 @@
+/*
+ * Copyright (C) 2021 The Android Open Source Project
+ *
+ * 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.
+ */
+
+package com.android.settings.homepage;
+
+/** Activity for other apps to launch Settings deep link page */
+public class DeepLinkHomepageActivity extends SettingsHomepageActivity {
+}