Minor cleanups to pentago:
Minor cleanups to pentago:

- Some minor formatting improvements to force clang-format to keep the spatial alignment
- Reduce a copy
- Move ToString to Move.

PiperOrigin-RevId: 288306781
Change-Id: I430b34f93714546938e74e5dd7462c8fb32e8250

deepmind/open_spiel,deepmind/open_spiel,deepmind/open_spiel,deepmind/open_spiel,deepmind/open_spiel,deepmind/open_spiel