Add Mozc Lattice Viewer web tool.

* This is a web tool to interactively see the Lattice class.
* It reads a TSV file generated from immutable_converter_main
  + e.g. immutable_converter_main --dictionary oss --query=もじ --output=lattice.tsv

#typingquality

PiperOrigin-RevId: 789660653

Author: hiroyuki-komatsu