AAPT2: Loosen loading apk format requirements

The Android runtime and AAPT are more lenient of apk format, allowing
for duplicate enty, types, and configs. This change loosens the
ResourceTable's checks on resource uniqueness when apks are loaded; not
when ResourceTables are being created by aapt2.

Bug: 36051266
Test: Tested using apks in bug with allow_duplicates on and off
Change-Id: I9296417bf2dc53e1e891479a53679a0388210d50
diff --git a/tools/aapt2/Resource.cpp b/tools/aapt2/Resource.cpp
index b78f48c..ae01170 100644
--- a/tools/aapt2/Resource.cpp
+++ b/tools/aapt2/Resource.cpp
@@ -96,6 +96,8 @@
       return "styleable";
     case ResourceType::kTransition:
       return "transition";
+    case ResourceType::kUnknown:
+      return "unknown";
     case ResourceType::kXml:
       return "xml";
   }