Replace entrypoint scripts with GoLang application

[P4sca1]

The idea is to replace the current bash / powershell entrypoint scripts with a GoLang application.

Advantages:

• No need to maintain nearly identical code in bash and powershell
• Easier code sharing of common utilities
• More powerful
• Sanitize arguments more easily by using exec.Command instead of eval with an arbitrary string

Instead of using environment configuration only, we could also support config files using
https://github.com/spf13/viper.

Directory structure:

game-images/
├── common/
│   └── module.go
├── games/
│   ├── game1/
│   │   ├── docker/
│   │   │   ├── Dockerfile.linux
│   │   │   ├── Dockerfile.windows
│   │   ├── entrypoint/
│   │   │   ├── main.go
│   ├── game2/
│   │   ├── docker/
│   │   │   ├── Dockerfile.linux
│   │   │   ├── Dockerfile.windows
│   │   ├── entrypoint/
│   │   │   ├── main.go
└── README.md

[P4sca1]

Ideally, there would be a GameConfiguration struct for each game, which defines all the co fig options and how they are mapped from / to config file / environment variable.

It would be great if other GoLang applications could import and create that struct and marshal into env variables.

[P4sca1]

Once this is implemented, providing a windows container version for all the games should be easier.