Summary:
This is step one on merging the `rnpm` config with the `cli config`. The plan is to remove two sources of truth (rnpm package.json config and rn-cli Javascript config)
Rationale:
As of now, we have `rnpm` config, that used to live in the `local-cli/core/config/index.js` and the `rn-cli` config, living in `default.config.js` and `utils/Config.js`.
This PR moves all the things into one file, called `local-cli/core', simplifies things, enhances types (Config now has better types, added missing properties and fixed descriptions).
One notable addition is that users can now opt-in to override the commands that are loaded at the package level. Previously it was only possible to add a command by writing a plugin. Now, you can just tweak the `rn-cli.config.js`.
This is one of the several improvements I have on my roadmap, with better documentation for the CLI as well.
Closes https://github.com/facebook/react-native/pull/11564
Differential Revision: D4360095
fbshipit-source-id: feaec7c88df63e51cef1f9620c7eedeb738d3d00
30e89b49f1