Retain parsed attribute type

If the value of an attribute enum is defined as a hexadecimal integer,
flatten uses of the attribute as with the
android::Res_value::TYPE_INT_HEX type.

This change adds a "type" field to pb::Attribute::Symbol, which if left
unset, will have a default value of android::Res_value::TYPE_INT_DEC
when deserialized by aapt2.

Bug: 124474141
Test: aapt2_tests and manual compilation of files and inspection using
`aapt2 dump chunks`
Change-Id: Ibf12394284fdbe3a8047f7ecf4fe68517dfc3abb
diff --git a/tools/aapt2/ResourceUtils.cpp b/tools/aapt2/ResourceUtils.cpp
index e0040e4..bd2ab53 100644
--- a/tools/aapt2/ResourceUtils.cpp
+++ b/tools/aapt2/ResourceUtils.cpp
@@ -378,7 +378,7 @@
     const ResourceName& enum_symbol_resource_name = symbol.symbol.name.value();
     if (trimmed_str == enum_symbol_resource_name.entry) {
       android::Res_value value = {};
-      value.dataType = android::Res_value::TYPE_INT_DEC;
+      value.dataType = symbol.type;
       value.data = symbol.value;
       return util::make_unique<BinaryPrimitive>(value);
     }