flyout: a11y: Allow users to control flyout menus with keyboard

This CL adds the ability for the user to use the keyboard to control the
flyout menus.

When the user selects an item with arrow keys and decides to proceed,
the `View`'s click listeneris called. We capture this and run the flyout
logic when necessary.

This CL also makes it so that `ListMenuItemAdapter` sets up the view to
use both the delegate and the click listener upon click.

Bug: 447103380
Change-Id: I4560508cdfe63fab553e44478bb48d3ed528caca
Reviewed-on: https://chromium-review.googlesource.com/c/chromium/src/+/6978443
Reviewed-by: Peter Conn <peconn@chromium.org>
Reviewed-by: Ted Choc <tedchoc@chromium.org>
Reviewed-by: Jenna Himawan <jhimawan@google.com>
Commit-Queue: Masa Fujita <massan@google.com>
Cr-Commit-Position: refs/heads/main@{#1527899}