Add config for Wi-Fi Hotspot Settings hidden

- Add config_show_wifi_hotspot_settings for Settings customization

- Hide Wi-Fi Hotspot preference in Hotspot & tethering Settings

- Don't launch Wi-Fi Hotspot Settings (e.g long press on Hotspot in QS-tile)

Bug: 213426762
Test: manual test
atest -c com.android.settings.wifi.WifiUtilsTest
make RunSettingsRoboTests ROBOTEST_FILTER=WifiTetherPreferenceControllerTest
make RunSettingsRoboTests ROBOTEST_FILTER=WifiTetherSettingsTest

Merged-In: I11f88d0d15d6d5c2766b64b5847ac31ed0f34c25
Change-Id: I11f88d0d15d6d5c2766b64b5847ac31ed0f34c25
(cherry picked from commit 160b5078ed)

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

@@ -18,6 +18,8 @@ package com.android.settings.wifi.tether;
 
 import static android.net.wifi.WifiManager.WIFI_AP_STATE_CHANGED_ACTION;
 
+import static com.android.settings.wifi.WifiUtils.canShowWifiHotspot;
+
 import android.app.settings.SettingsEnums;
 import android.content.BroadcastReceiver;
 import android.content.Context;
@@ -107,6 +109,13 @@ public class WifiTetherSettings extends RestrictedDashboardFragment
     @Override
     public void onCreate(Bundle icicle) {
         super.onCreate(icicle);
+        if (!canShowWifiHotspot(getContext())) {
+            Log.e(TAG, "can not launch Wi-Fi hotspot settings"
+                    + " because the config is not set to show.");
+            finish();
+            return;
+        }
+
         setIfOnlyAvailableForAdmins(true);
         mUnavailable = isUiRestricted() || !mWifiRestriction.isHotspotAvailable(getContext());
     }