Add the assisted dialing carrier config.

This is used to activate the feature and show the settings.

Remove @hide from the public APIS.

Design doc:
go/assisted-dialing-dd-v1

Test: manual
Bug: 63934304
Change-Id: I09ea52720bf2439537e2f4ad32afb14f5df25f71
diff --git a/telecomm/java/android/telecom/Connection.java b/telecomm/java/android/telecom/Connection.java
index aaef8d3..7522443 100644
--- a/telecomm/java/android/telecom/Connection.java
+++ b/telecomm/java/android/telecom/Connection.java
@@ -35,6 +35,7 @@
 import android.os.Looper;
 import android.os.Message;
 import android.os.ParcelFileDescriptor;
+import android.os.Parcelable;
 import android.os.RemoteException;
 import android.os.SystemClock;
 import android.util.ArraySet;
@@ -401,7 +402,6 @@
 
     /**
      * Set by the framework to indicate that a connection is using assisted dialing.
-     * @hide
      */
     public static final int PROPERTY_ASSISTED_DIALING_USED = 1 << 9;
 
@@ -2538,6 +2538,19 @@
     }
 
     /**
+     * Adds a parcelable extra to this {@code Connection}.
+     *
+     * @param key The extra key.
+     * @param value The value.
+     * @hide
+     */
+    public final void putExtra(@NonNull String key, @NonNull Parcelable value) {
+        Bundle newExtras = new Bundle();
+        newExtras.putParcelable(key, value);
+        putExtras(newExtras);
+    }
+
+    /**
      * Removes extras from this {@code Connection}.
      *
      * @param keys The keys of the extras to remove.