[Wi-Fi] Add STA+AP information in Hotspot & tethering footer

Use WifiManager#isStaApConcurrencySupported() to check if a
device supports STA+AP and shows the footer information.

Bug: 121328949
Test: make RunSettingsRoboTests ROBOTEST_FILTER=TetherSettingsTest
      make RunSettingsRoboTests ROBOTEST_FILTER=WifiTetherFooterPreferenceControllerTest
Change-Id: I3446abb5cc9cdf76da8d17f5de31bd65715c165c

src/com/android/settings/wifi/tether/WifiTetherBasePreferenceController.java

@@ -26,6 +26,7 @@ import androidx.preference.PreferenceScreen;
 import com.android.settings.core.PreferenceControllerMixin;
 import com.android.settingslib.core.AbstractPreferenceController;
 
+// TODO(b/151133650): Replace AbstractPreferenceController with BasePreferenceController.
 public abstract class WifiTetherBasePreferenceController extends AbstractPreferenceController
         implements PreferenceControllerMixin, Preference.OnPreferenceChangeListener {
 

src/com/android/settings/wifi/tether/WifiTetherFooterPreferenceController.java

@@ -0,0 +1,54 @@
+/*
+ * Copyright (C) 2020 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.wifi.tether;
+
+import android.content.Context;
+
+import androidx.preference.Preference;
+
+import com.android.settings.R;
+
+/**
+ * Shows hotspot footer information.
+ */
+public class WifiTetherFooterPreferenceController extends WifiTetherBasePreferenceController {
+
+    private static final String PREF_KEY = "tether_prefs_footer_2";
+
+    public WifiTetherFooterPreferenceController(Context context) {
+        super(context, null /* listener */);
+    }
+
+    @Override
+    public String getPreferenceKey() {
+        return PREF_KEY;
+    }
+
+    @Override
+    public void updateDisplay() {
+        if (mWifiManager.isStaApConcurrencySupported()) {
+            mPreference.setTitle(R.string.tethering_footer_info_sta_ap_concurrency);
+        } else {
+            mPreference.setTitle(R.string.tethering_footer_info);
+        }
+    }
+
+    @Override
+    public boolean onPreferenceChange(Preference preference, Object newValue) {
+        return true;
+    }
+}