onCancel should fire in AlertDialog if Escape is pressed

# 🐛 Bug Report (or maybe feature request?)

When adding an `onCancel` handler to an AlertDialog, it should fire if the dialog is closed via the Escape key.

See here for a repro: https://codesandbox.io/s/adoring-meadow-7cl4c?file=/src/App.js

Open the dialog, click Cancel, dialog will close, you'll see 'Canceled' in the console.
Open the dialog, press Escape key, dialog will close, no 'Canceled' in the console.

Start with the reproduction in src/App.js from the linked CodeSandbox and trace the AlertDialog Escape-key dismissal path. Confirm that closing with Escape invokes onCancel and that the existing click-Cancel behavior still logs “Canceled”.

Written by the indexing model from the issue text.