Added @UsedForTesting to 'missing' methods to avoid ProGuard removing them

java/src/com/android/inputmethod/latin/BinaryDictionary.java

.../com/android/inputmethod/latin/DictionaryFacilitator.java

.../android/inputmethod/latin/utils/DictionaryInfoUtils.java

...com/android/inputmethod/latin/utils/DistracterFilter.java

...m/android/inputmethod/latin/utils/LanguageModelParam.java