message: Add <StringView> natvis tag for rdcstr
diff: <Type Name="rdcstr">
  <DisplayString Condition="elems == 0">""</DisplayString>
  <DisplayString>{elems,s}</DisplayString>
  + <StringView>elems,s</StringView>
  <Expand>
  <Item Name="[size]" ExcludeView="simple">usedCount</Item>
  <Item Name="[capacity]" ExcludeView="simple">allocatedCount</Item>
  