Layoutlib: New bridge implementation using the new API 5.

Since the new API prepare for stateful layoutlib, major
reorganization of the code.

New "android" sub-package for all extended android classes.
  Also moved BridgeInflater in here so that all extended classes
  are in this package. Only delegates and classes replacing
  renamed classes are in their original android.* packages.
  Also created full file for the empty implementations of
  IWindow and IWindowSession.
New "impl" for the dirty work implementation.
Main package contains the basic implementation of the API.

Most of the code that was in Bridge is now in .impl.LayoutSceneImpl,
with the main init/inflate/render code split into the contrustrutor,
inflate() and render().

Change-Id: Ie15b15e5a1b2388cd6ef82e518345b1fc02ec981