🛠 🏞 💾 Add kafka-streams support for game lobby

[Terkwood]

Add kafka-level support for private and public games

Advances #42.

Todo

• rename topics
• initialize bugout-game-lobby-commands topic once, on docker-compose up: tiny container?
• try inner joins
• sanitize breadcrumb trail: track clientId as creator of the game
• better naming for lobby domain objects / main program
• impl private game creation
• impl private game joining
• impl public game find
• impl public game creation
• impl public game join branch
• impl changelog step
• impl game-ready stream step
• impl wait-for-opponent step
• test private game creation
• test private game joining
• test public game find
• test public game creation
• test public game join branch
• test changelog step
• test game-ready stream step
• test wait-for-opponent step
• address code TODOs
• address GH comment TODOs
• clean dockerfiles

[Terkwood]

Need to track a creator: ClientId field in the lobby, so that we can destroy any games originated by a user who disconnects before being matched with another user