Add RFC: alternative format for package.json

[Timmmm]

Draft RFC to add an alternative format for package.json that allows comments.

I need to look into the implementation, and I'm sure there will be bikeshedding over the actual format chosen.

Fixes #291

See also https://github.com/npm/cli/issues/8751

[ljharb]

As has been discussed elsewhere, if there's not a built-in way to node (or javascript) to work with a format, then it's going to be impractical for the entire ecosystem of tooling to work with it.

[Timmmm]

The impact will be that if they want to support this optional format they need to install the json5 package (or whichever format we use). I don't understand how that is a significant issue.

[ljharb]

What npm supports, every tool effectively must support. Why force an additional package on the entire ecosystem? That's an incredibly high cost merely for slightly more ergonomic comments.

[Timmmm]

What npm supports, every tool effectively must support.

This alternative format is optional. Third party tools can decide if they want to support it (potentially losing users) and users can decide if they want to use it (potentially losing third party tools).

Anyone that doesn't like it can happily continue using package.json as before.

slightly more ergonomic comments

It's not slightly more ergonomic comments. It's vastly more ergonomic comments for scripts and the top of the file, and it enables comments at all for dependencies which is where you really want them.