Add Quarto game

[edawite]

Summary

• add the standard two-player Quarto board game as a deterministic, perfect-information C++ game
• model the piece-selection and placement phases, all 16 four-attribute pieces, win detection, undo, structured state/action APIs, and tensor observations
• add focused rule tests, 100 random simulations, registry/docs updates, and a generated regression playthrough

Validation

• ctest --output-on-failure -R '^quarto_test$'
• python3 open_spiel/python/tests/pyspiel_test.py (71 tests)
• replayed open_spiel/integration_tests/playthroughs/quarto.txt
• cpplint on the new C++ sources

Refs #843

[lanctot]

Hi @edawite , I would love to have Quarto in OpenSpiel. It is commercial game, so we will have to consult with our legal team. You don't happen to have any connection to the publishers, do you?

I have added a point to the PR contributor's README (#1511) to help make this point clear, because it may not be immediately get imported.