AAPT2: Ensure style strings are always first in StringPool

Move the styled strings to a separate section of the StringPool so
that sorting can never mess up the order of Styles.

Bug: 63570514
Test: make aapt2_tests
Change-Id: Id2ce1355b92be1bb31ce0daa7e54ae9b5b6c2ffe
diff --git a/tools/aapt2/proto/TableProtoDeserializer.cpp b/tools/aapt2/proto/TableProtoDeserializer.cpp
index 4b56192..37d5ed0 100644
--- a/tools/aapt2/proto/TableProtoDeserializer.cpp
+++ b/tools/aapt2/proto/TableProtoDeserializer.cpp
@@ -195,8 +195,7 @@
           spans++;
         }
         return util::make_unique<StyledString>(pool->MakeRef(
-            style_str,
-            StringPool::Context(StringPool::Context::kStylePriority, config)));
+            style_str, StringPool::Context(StringPool::Context::kNormalPriority, config)));
       }
       return util::make_unique<String>(
           pool->MakeRef(str, StringPool::Context(config)));