fix: make ESM module

[Skn0tt]

Closes https://github.com/blitz-js/babel-plugin-superjson-next/issues/145.

The code we were compiling into dist was CJS, not ESM. But when the user installed SuperJSON 2, which is ESM-only, it tried require-ing it. That failed, see #145. This PR fixes that, by making this package (including /tools) an ESM package as well.

[Skn0tt]

@mongolyy I prereleased this as v0.4.6-0, could you check if that fixes your problem before we release this?

[mongolyy]

@Skn0tt Thanks for the improvement.

Unfortunately, however, my application fails with an error when I run the next build or next dev command. I am attaching a terminal log from when I ran the next build command.

$ next build
 ✓ Linting and checking validity of types
   Disabled SWC as replacement for Babel because of custom Babel configuration ".babelrc" https://nextjs.org/docs/messages/swc-disabled
   Using external babel configuration from C:\Users\mongolyy\repos\next-app\app\.babelrc
Failed to compile.

./src/pages/_app.tsx
Error: [BABEL]: You appear to be using a native ECMAScript module plugin, which is only supported when running Babel asynchronously. (While processing: C:\Users\mongolyy\repos\next-app\app\node_modules\babel-plugin-superjson-next\dist\index.js)
    at loadCjsOrMjsDefault (C:\Users\mongolyy\repos\next-app\app\node_modules\next\dist\compiled\babel\bundle.js:1:35044)
    at loadCjsOrMjsDefault.next (<anonymous>)
    at requireModule (C:\Users\mongolyy\repos\next-app\app\node_modules\next\dist\compiled\babel\bundle.js:1:41464)
    at requireModule.next (<anonymous>)
    at loadPlugin (C:\Users\mongolyy\repos\next-app\app\node_modules\next\dist\compiled\babel\bundle.js:1:38200)
    at loadPlugin.next (<anonymous>)
    at createDescriptor (C:\Users\mongolyy\repos\next-app\app\node_modules\next\dist\compiled\babel\bundle.js:1:23608)
    at createDescriptor.next (<anonymous>)
    at evaluateSync (C:\Users\mongolyy\repos\next-app\app\node_modules\next\dist\compiled\babel\bundle.js:1910:740999)
    at C:\Users\mongolyy\repos\next-app\app\node_modules\next\dist\compiled\babel\bundle.js:1910:738372

However, I think this can be worked around by babel configuration, so I will try trial and error. I will comment here if I make progress. If you have any advice, I would appreciate it.