Switch from SI to IEC unit when formatting data usage bytes

- Created a new helper method DataUsageUtils.formatDataUsage() to
  format data usage bytes using IEC formatting.
- Switch from Formatter.formatFileSize() to DataUsageUtils.formatDataUsage()
  everywhere in datausage package.

Change-Id: I9323beed8bf5126b153fc9a3cdd9591c97ca6fd2
Bug: 76159924
Test: robotests

src/com/android/settings/datausage/ChartDataUsagePreference.java

@@ -27,6 +27,7 @@ import android.text.format.Formatter;
 import android.text.style.ForegroundColorSpan;
 import android.util.AttributeSet;
 import android.util.SparseIntArray;
+
 import com.android.settings.R;
 import com.android.settings.Utils;
 import com.android.settings.graph.UsageView;
@@ -155,7 +156,7 @@ public class ChartDataUsagePreference extends Preference {
 
     private CharSequence getLabel(long bytes, int str, int mLimitColor) {
         Formatter.BytesResult result = Formatter.formatBytes(getContext().getResources(),
-                bytes, Formatter.FLAG_SHORTER);
+                bytes, Formatter.FLAG_SHORTER | Formatter.FLAG_IEC_UNITS);
         CharSequence label = TextUtils.expandTemplate(getContext().getText(str),
                 result.value, result.units);
         return new SpannableStringBuilder().append(label, new ForegroundColorSpan(mLimitColor), 0);