Move header reading methods to policyimpl.

.../src/suggest/core/dictionary/binary_dictionary_header.cpp

...ni/src/suggest/core/dictionary/binary_dictionary_header.h

...ore/dictionary/binary_dictionary_header_reading_utils.cpp

.../core/dictionary/binary_dictionary_header_reading_utils.h

.../jni/src/suggest/core/dictionary/binary_dictionary_info.h

native/jni/src/suggest/core/dictionary/dictionary.cpp

native/jni/src/suggest/core/dictionary/dictionary.h

native/jni/src/suggest/core/dictionary/digraph_utils.cpp

native/jni/src/suggest/core/dictionary/digraph_utils.h

.../suggest/core/policy/dictionary_header_structure_policy.h

...est/core/policy/dictionary_structure_with_buffer_policy.h

native/jni/src/suggest/core/session/dic_traverse_session.cpp

native/jni/src/suggest/core/suggest.cpp

...gest/policyimpl/dictionary/dynamic_patricia_trie_policy.h

.../src/suggest/policyimpl/dictionary/patricia_trie_policy.h