Introduce BinaryDictionaryHeader to access binary dictionary header.

BinaryDictionaryHeader abstracts header structure and access header information via only its instance.

Bug: 6669677

Change-Id: Ib5ab0e8fef12265ddabc1d0165548b69953bba6a
diff --git a/native/jni/Android.mk b/native/jni/Android.mk
index 7ca4057..9718cf5 100644
--- a/native/jni/Android.mk
+++ b/native/jni/Android.mk
@@ -55,7 +55,9 @@
         dic_nodes_cache.cpp) \
     $(addprefix suggest/core/dictionary/, \
         bigram_dictionary.cpp \
-        binary_dictionary_format.cpp \
+        binary_dictionary_format_utils.cpp \
+        binary_dictionary_header.cpp \
+        binary_dictionary_header_reading_utils.cpp \
         byte_array_utils.cpp \
         dictionary.cpp \
         digraph_utils.cpp) \