Version up dynamic dict format from 401 to 402.

...android/inputmethod/latin/ExpandableBinaryDictionary.java

...rc/com/android/inputmethod/latin/makedict/FormatSpec.java

.../src/suggest/policyimpl/dictionary/header/header_policy.h

.../policyimpl/dictionary/header/header_read_write_utils.cpp

...cture/dictionary_structure_with_buffer_policy_factory.cpp

...t/policyimpl/dictionary/utils/dict_file_writing_utils.cpp

.../src/suggest/policyimpl/dictionary/utils/format_utils.cpp

...ni/src/suggest/policyimpl/dictionary/utils/format_utils.h

...roid/inputmethod/latin/BinaryDictionaryDecayingTests.java

.../com/android/inputmethod/latin/BinaryDictionaryTests.java