Add more default extensions to resolve .mjs & .wasm & .json

[KyleAMathews]

fixes #8246
fixes #7581

[kkemple]

👍

[KyleAMathews]

These are all default resolvable extensions in webpack so we should add them. NPM packages are starting to ship .mjs files which people are running into trouble with.

[DSchau]

LGTM, apart from my comment.

[jquense]

my only concern here is it dramatically increases the pathnames webpack has to stat to resolve one file...my hunch would be to only support what Node does out of the box

[KyleAMathews]

my hunch would be to only support what Node does out of the box

Agreed — other than wasm (and jsx), this is now what node support out of the box.

[KyleAMathews]

Yarn registry killed appveyor :-| merging as otherwise is working.

[alpgumus]

This doesn't seem to fix #7581 unless:
(actually, it is complaining about mjs files unless:)

actions.setWebpackConfig({
    module: {
      rules: [
        {
          test: /\.mjs$/,
          type: 'javascript/auto',
        },
      ],
    },
})

[KyleAMathews]

Hmm ok. Could you open a new issue with a reproduction?