Improve serverless operation guide and support general use cases

[floydkim]

Since AppCenter is retiring, CodePush’s cloud infrastructure may also be discontinued.
The code-push-server repository provides self-hosted code, but teams using CodePush now need to manage their own API servers. Currently, the cloud infrastructure option is limited to Azure.

So, I think it makes sense for our repository to aim at becoming a serverless successor.

However, the current implementation only supports the deployment strategy used in the “Soomgo” app service, and other use cases haven’t been considered yet. While we don’t plan to cover every deployment strategy, it’s important to ensure our tool works well in common scenarios.

Let’s consider offering documentation and implementations that cover more general use cases.