Move xmlParserUtils to core

This class is currently used by both search and slice, in the future
will be used by DashboardFragment to build controller list. So the scope
of this class is beyond search now.

Test: rerun robotests
Change-Id: If43ebca065aac31ad24f95a94bfe5be784109605

tests/unit/src/com/android/settings/core/UniquePreferenceTest.java

@@ -36,7 +36,6 @@ import com.android.settings.search.DatabaseIndexingUtils;
 import com.android.settings.search.Indexable;
 import com.android.settings.search.SearchIndexableRaw;
 import com.android.settings.search.SearchIndexableResources;
-import com.android.settings.search.XmlParserUtils;
 
 import org.junit.Before;
 import org.junit.Test;
@@ -203,7 +202,7 @@ public class UniquePreferenceTest {
                     continue;
                 }
                 final AttributeSet attrs = Xml.asAttributeSet(parser);
-                final String key = XmlParserUtils.getDataKey(mContext, attrs);
+                final String key = PreferenceXmlParserUtils.getDataKey(mContext, attrs);
                 if (TextUtils.isEmpty(key)) {
                     Log.e(TAG, "Every preference must have an key; found null key"
                             + " in " + className