chore: follow gRPC example architecture for example apps

[D4ryl00]

This PR moves the example apps into directories depending on the client implementation language. Because we are using gRPC, we wanted to follow this docs from gRPC to help users easily find the client implementation they want.

This is the new architecture:

examples
├── csharp-dotnet
│   └── UnityClient
├── go
│   └── goclient
└── js
    ├── react-native
    │   ├── gnoboard
    │   └── hello
    └── wails

Tests done: Compiling gnoboard (Android / iOS), hello (Android / iOS), wails (iOS)