Refactor factories

Change module factories from returning a blueprint.Module and a list
of property structs to returning an android.Module, which holds the
list of property structs.

Test: build.ninja identical except for Factory: comment lines
Change-Id: Ica1d823f009db812c518f271a386fbff39c9766f

cc/coverage.go

@@ -16,6 +16,7 @@ package cc
 
 import (
 	"android/soong/android"
+
 	"github.com/google/blueprint"
 )