[Provider Model] 1. Use the original string for Calls & SMS 2. Set preferred status in Call & SMS

1.
UX modify the string in document

Dual SIMs:
    Calls & SMS
    Google Fi (preferred), AT&T

    Calls & SMS
    Google Fi (preferred for calls), AT&T (preferred for SMS)

    Calls & SMS
    Google Fi (Temporarily unavailable), AT&T

Single SIM:
    Calls & SMS
    Temporarily unavailable

2.
UX: https://screenshot.googleplex.com/B9BETTwRoa4mfds.png
Implementation: https://screenshot.googleplex.com/4vxMLBynwdTvhEs.png

Bug: 178916743
Test: make
Change-Id: I444eb0e3361707764dae18b9fa942c7f7a80a2c6

src/com/android/settings/network/telephony/SmsDefaultSubscriptionController.java

@@ -21,6 +21,8 @@ import android.telecom.PhoneAccountHandle;
 import android.telephony.SubscriptionInfo;
 import android.telephony.SubscriptionManager;
 
+import com.android.settings.Utils;
+
 public class SmsDefaultSubscriptionController extends DefaultSubscriptionController {
 
     private final boolean mIsAskEverytimeSupported;
@@ -56,4 +58,13 @@ public class SmsDefaultSubscriptionController extends DefaultSubscriptionControl
         // Not supporting calling account override by VoIP
         return null;
     }
+
+    @Override
+    public CharSequence getSummary() {
+        if (Utils.isProviderModelEnabled(mContext)) {
+            return MobileNetworkUtils.getPreferredStatus(mContext, mManager, false);
+        } else {
+            return super.getSummary();
+        }
+    }
 }