Replace Toast-based cheat sheets with tooltips

Currently ActionMenuItemView, MediaRouteButton and
ScrollingTabContainerView each have their own
implementation of a Toast-based long-press tooltips
(the last two apparently copy/pasted from the first).

Replacing those with the recently introduced tooltips
supported by the framework.

Bug: 31516506
Test: manual in ApiDemos
Change-Id: Ibcb8c5a43577a8b4d30f1a26e48ddcfde015d1dc