Refactoring: PtNodeWriter to separate version specific writing methods.

native/jni/Android.mk

...olicyimpl/dictionary/structure/pt_common/pt_node_params.h

...olicyimpl/dictionary/structure/pt_common/pt_node_writer.h

...structure/v3/dynamic_patricia_trie_gc_event_listeners.cpp

...y/structure/v3/dynamic_patricia_trie_gc_event_listeners.h

...ionary/structure/v3/dynamic_patricia_trie_node_writer.cpp

...ctionary/structure/v3/dynamic_patricia_trie_node_writer.h

.../dictionary/structure/v3/dynamic_patricia_trie_policy.cpp

...pl/dictionary/structure/v3/dynamic_patricia_trie_policy.h

...ary/structure/v3/dynamic_patricia_trie_writing_helper.cpp

...onary/structure/v3/dynamic_patricia_trie_writing_helper.h