[Settings] Disable gear button if user is not admin.

- Mobile settings include many settings which second user shall not
  modify, so make gear button disabled to avoid second user want to try.

Bug: 184303943
Test: Maunal test passeded
Test: atest passed.
Change-Id: Ic04fa71772df4ac424965ad2ca95733b1e15d6a7

tests/unit/src/com/android/settings/network/SubscriptionsPreferenceControllerTest.java

@@ -40,6 +40,7 @@ import android.net.ConnectivityManager;
 import android.net.Network;
 import android.net.NetworkCapabilities;
 import android.os.Looper;
+import android.os.UserManager;
 import android.provider.Settings;
 import android.telephony.ServiceState;
 import android.telephony.SignalStrength;
@@ -81,6 +82,8 @@ import java.util.List;
 public class SubscriptionsPreferenceControllerTest {
     private static final String KEY = "preference_group";
 
+    @Mock
+    private UserManager mUserManager;
     @Mock
     private SubscriptionManager mSubscriptionManager;
     @Mock
@@ -121,10 +124,12 @@ public class SubscriptionsPreferenceControllerTest {
         when(mContext.getSystemService(SubscriptionManager.class)).thenReturn(mSubscriptionManager);
         when(mContext.getSystemService(ConnectivityManager.class)).thenReturn(mConnectivityManager);
         when(mContext.getSystemService(TelephonyManager.class)).thenReturn(mTelephonyManager);
+        when(mContext.getSystemService(UserManager.class)).thenReturn(mUserManager);
         when(mTelephonyManager.createForSubscriptionId(anyInt())).thenReturn(mTelephonyManager);
         when(mConnectivityManager.getActiveNetwork()).thenReturn(mActiveNetwork);
         when(mConnectivityManager.getNetworkCapabilities(mActiveNetwork))
                 .thenReturn(mNetworkCapabilities);
+        when(mUserManager.isAdminUser()).thenReturn(true);
         when(mLifecycleOwner.getLifecycle()).thenReturn(mLifecycleRegistry);
 
         mPreferenceManager = new PreferenceManager(mContext);