Updates NotificationInfo layout/buttons.

This change modifies the UI displayed when the new interruption model is
enabled after long pressing a notification or tapping the settings icon
in the notification side menu.  The text links for blocking the channel,
toggling its importance, or canceling out of the dialog are replaced
with buttons with icons and clearer text descriptions.

Test: atest NotificationInfoTest
Bug: 116622974
Change-Id: I06ead5c4da77319df3ebe4c48d863dede37bf2f4