Split InputFlinger into multiple libraries

This is the InputFlinger FE/BE split as detailed in
go/arc++inputflinger-split.

We split libinputflinger into the following dynamic libraries:
- libinputflinger: Acts as the frontend for inputflinger and implements
      InputDispatcher and InputManager.
- libinputreader: Acts as the backend for inputflinger and impliements
      InputReader and EventHub, and adds a InputReaderFactory to create
      the InputReader.
- libinputflinger_base: Contains the common logic that is shared
      throughout InputFlinger, and contains the definitions for
      InputReaderInterface (in InputReaderBase.h) and
      InputListenerInterface (in InputListener.h).

Bug: 119264687
Test: manual: Build, run, and test input (touch, mouse)
Change-Id: I8567635f48de58ee8e5bdb0f8a17a73ea6fa37ef