Add npm for project build and pnpm for monorepo management

[joaquimrocha]

We have currently make and npm, where make just calls npm and go for building the frontend and backend, respectively. While this is common for many Linux developers, it's not common for many Js ones, and there's no real reason why make is needed. So we should add a packages.json to the root folder of the project and use it to build the project just having node + go.

Since we have also 3 npm projects in Headlamp (frontend, app, and headlamp-plugin, not counting the example plugins), we could also a tool for managing monorepos, like pnpm. Same for the plugins repo.

• [ ] Make the project buildable by just using npm run scripts
• [ ] Set the Makefile as deprecated (print warnings in commands)
• [ ] Use pnpm in order to manage the different build options and npm sub-projects (headlamp-plugin, frontend, app)