Adds initial action to NotificationInfo menu items.

This change modifies the mechanism for creating items in
NotificationMenuRow which open the NotificationInfo panel such that they
can optionally specify an action to take immediately - specifically,
blocking the channel or toggling its priority.

This will allow us to add buttons for these actions to the menu row on
the right side of the notification.

Bug: 116622974
Test: atest NotificationInfoTest NotificationGutsManagerTest
Change-Id: If87bd4f48907efa692810a6bfef1aa85251f3e38