Implement a scalable deployment infrastructure

[yann510]

• Auto deploy when a pull request is merged on master using Github Actions (if possible only affected apps)
• Implement automatic scaling which can be configured through code/config file
• Deploy self contained review apps on pull requests
• Update the readme to reflect the new steps needed when using this project as a template

I was thinking maybe we could use Kubernetes, but one thing I don't like about it is the complexity which is often way too high for simple projects. Since this is a template project, make it as simple as possible with detailed instructions. We can use other tools if we see fit.

[yann510]

If we are unable to cache node_modules, here is an interesting benchmark: