Add handling of "replacement" key events in InputReader and EventHub by
consulting device's character key map (if exists) for presence of
replacement key code for given get code and meta state combination,
before passing it to InputDispatcher.
This enables defining special keys, such as ESC, on keyboards lacking
enough physical keys, via combination of normal keys and modifiers, for
example AltR + 1 => ESC.
Bug: 24504154
Change-Id: I7e36104808bedcf724436c1fbb63d37c35cca8af
0faaa0bd7a