Refactor policy parsing

This change removes the ability for an overlayable resource to be
defined in multiple policy blocks within the same overlayable. This
change also changes aapt2 to use a bit mask to keep track of the parsed
policies.

Bug: 110869880
Bug: 120298168
Test: aapt2_tests
Change-Id: Ie26cd913f94a16c0b312f222bccfa48f62feceaa
diff --git a/tools/aapt2/cmd/Dump.h b/tools/aapt2/cmd/Dump.h
index 89d19cf..5cf056e 100644
--- a/tools/aapt2/cmd/Dump.h
+++ b/tools/aapt2/cmd/Dump.h
@@ -255,6 +255,7 @@
     AddOptionalSubcommand(util::make_unique<DumpXmlStringsCommand>(printer, diag_));
     AddOptionalSubcommand(util::make_unique<DumpXmlTreeCommand>(printer, diag_));
     AddOptionalSubcommand(util::make_unique<DumpBadgerCommand>(printer), /* hidden */ true);
+    // TODO(b/120609160): Add aapt2 overlayable dump command
   }
 
   int Action(const std::vector<std::string>& args) override {