Move list of public libraries to a config file

This list contains libraries that should directly or indirectly
be accessible to apps for the platform. Note that this list is
not device specific but rather device class specific.

For now we have 2 separate lists; one for Android Phones and Tablets,
and another one for Android Wear devices.

Bug: http://b/27546414
Bug: http://b/22548808
Change-Id: I83de5e3cf67392d0e9af66f70123898bd5997146