Show popup for aggregation suggestion

- create ListPopupWindow instead of embedding Views into
  the base layout.
- refrain AggregationSuggestionView from having focusable and
  clickable capability, which will be automatically supplied from
  ListView
- tweak layout xmls to show ListPopupWindow correctly. Include
  some pixel-perfect designs

Bug: 5057400
Change-Id: I9ec8642c0864204747ee445da7ee0292171a8788