Fix mismatched types between entrypoint and pure modules

[fruchtose-stripe]

Summary & motivation

This change addresses #563. Types from pure and the main entrypoint are not interchangeable since rollup-plugin-dts generates two separate sets of types. This fixes the issue and keeps the .d.mts files by copying the .d.ts files from the types directory into ./dist in two copies: one with the .d.ts extension, and with the .d.mts extension as well.

I've also made two directories for module entrypoints so that the main and pure entrypoints live in sister folders lib and pure. This helps with testing and standardization.

Testing & documentation

I tested these changes with a number of sample repos, as well as with the react-stripe-js repo. I also checked with arethetypeswrong and publint.

[winnie-stripe]

morale stamp

[esetnik]

@fruchtose-stripe I am seeing the following in our jest tests after updating to v3.0.9

   Cannot find module '../dist/stripe' from 'node_modules/@stripe/stripe-js/lib/index.js'

    Require stack:
      node_modules/@stripe/stripe-js/lib/index.js
      src/App.tsx
      test/test-utils.tsx
      src/Components/__tests__/PickerMulti.tsx
      ```

[yaskor]

Same problem as esetnik here:

X [ERROR] Could not resolve "../dist/stripe.mjs"

node_modules/@stripe/stripe-js/lib/index.mjs:1:14:
  1 │ export * from '../dist/stripe.mjs';

Created Issue...
Downgrade doesn't work...

[fruchtose-stripe]

Hi all. Thank you for the reports. This pull request has been reverted in issue v3.0.10. Please use that version instead.