Add "module" entry to package.json of all packages

[jaydenseric]

It would be great if all transpiled Apollo packages had a package.json module entry, pointing to an ES modules build. Modern tools such as Rollup and Webpack 2 prefer to consume ESM to do better tree-shaking, etc. It's also a lot nicer to read when debugging than CJS transpilation output.

See the Rollup wiki entry, and this Webpack issue.

Creating an issue here first for discussion, instead of in each individual repo.

[helfer]

@jaydenseric I'm not very familiar with the intricacies of packaging, but that sounds like a reasonable thing to do. I believe we already have it for Apollo Client, and @calebmer was planning to improve it and also change the build of react-apollo.

[helfer]

Hey @jaydenseric, I think we have modules for apollo-client. Which specific repos would you like to have module entries for? Feel free to make PRs to add them there.