Provide a working Hydra Chess game on mainnet with simple GUI

[abailly-iohk]

What

• Users can play Hydra Chess on mainnet through a simple GUI, using a laptop, and have their games' results tracked
• This is the Cobbled road version of Hydra Chess game

How

• Complete on-chain scrips handling players' results and status
  • Those scripts are currently mostly empty shells that should be completed to ensure some safety to end users
  • In particular, a user should never have their funds locked inside a head or if a head is closed
• Provide an "easy" way to define which peer a user connects to to play a game
• Complete Chess Game contract logic
  • Castling, pawn's en passant capture, and draws are not covered
• Provide a GUI using some local HTTP server + web page
  • @rezabaram Started work in this direction and it should be reasonably straightforward to do as we already have some experience communicating with a Hydra head from a browser thanks to Hydra Poll dApp #1110 and Hydraw
• Publish current ratings somewhere by following the chain
  • This would be useful to communicate about the game with the community
• Use Mithril to bootstrap node
  • This is not currently done as the shipped cardano-node is 8.7.1-pre which is not the one used to build mithril snapshots which implies users still pay the replay cost which limits the usefulness of Mithril