AAPT2: Implement density stripping and initial Split support

When a preferred density is supplied, the closest matching densities
will be selected, the rest stripped from the APK.

Split support will be enabled in a later CL. Command line support is still
needed, but the foundation is ready.

Bug:25958912
Change-Id: I56d599806b4ec4ffa24e17aad48d47130ca05c08
diff --git a/tools/aapt2/process/IResourceTableConsumer.h b/tools/aapt2/process/IResourceTableConsumer.h
index a2528d2..3a88044 100644
--- a/tools/aapt2/process/IResourceTableConsumer.h
+++ b/tools/aapt2/process/IResourceTableConsumer.h
@@ -40,6 +40,7 @@
     virtual StringPiece16 getCompilationPackage() = 0;
     virtual uint8_t getPackageId() = 0;
     virtual NameMangler* getNameMangler() = 0;
+    virtual bool verbose() = 0;
 };
 
 struct IResourceTableConsumer {