Allow filtering Inspector widget tree by library or package

As part of this, we may also want to show the widget creation location (or even definition location) in the widget details tree view.

No file, test, or entry point is named. Start by locating the Inspector widget tree implementation and determine how filtering by library or package should work, then clarify whether creation or definition locations are also required and what acceptance tests would demonstrate completion.

Scritto dal modello di indicizzazione a partire dal testo della issue.