feat: stargate receiver

[kuchmenko]

• Implement starage receive lzCompose contract
• Add multicalls handling
• Deployment docs + .env.example

[0xh3rman]

Things to improve:

1. we can refactor the folder structure a little bit to share same forge-std submodule
2. let's make multicall a separate Contract for reuse if possible, somthing like contract GemStargateReceiver is MulticallHandler, ILayerZeroComposer
3. Add github action to do deployment

I will work on 3

[0xh3rman]

can you rename folder shared to library?

[0xh3rman]

Thanks for the efforts to continue improving, I left some more comments, the ReentrancyGuard should be added back