When getting a widget provider by name, check all categories

Some widgets have different categories for special cases for Pixel
widgets and because of that, some times we can't find the provider,
so we need to go through all of the categories.

Flag: NA
Test: Manaul testing =(
Test: All widgets in widget_section.xml with alsoKeepInApp set to false will previously dissapear on the preview.
Fix: 331628371
Change-Id: Iffbb788cbb27c79a215d06d21c9d623462d6f7e6