Consider WidgetSections for suggestions in standalone picker

This cl address the problem for standalone picker (follow up to match
ag/27720721) to ensure widgets that aren't in section of their owning
package didn't appear in suggestions

Bug: 345520128
Test: Unit tests
Flag: EXEMPT bugfix
Change-Id: Ia0ef96c5be77db56b84c76ace498125d07f4be42