Support node16 module resolution for CJS projects

[myftija]

Background

CJS projects with moduleResolution set to node16 currently cannot consume modules published using dual-publish. The root cause is in the package.json exports. See this issue for more details: ai/nanoid#422.

Changes in this PR

• If there is a .d.ts types file specified in package.json, it is cloned into a .d.cts types file. Typescript can correctly interpret this as a CJS module.
• The require and import conditions in exports now each contain types and default conditions. This way we can use separate type files for ESM and CJS.

The generated exports field now looks like this:

"exports": {
  ".": {
    "browser": "./index.browser.js",
    "require": {
      "types": "./index.d.cts",
      "default": "./index.cjs"
    },
    "import": {
      "types": "./index.d.ts",
      "default": "./index.js"
    },
    "default": "./index.js"
  }
}

instead of:

"exports": {
  ".": {
    "types": "./index.d.ts",
    "browser": "./index.browser.js",
    "require": "./index.cjs",
    "import": "./index.js",
    "default": "./index.js"
  }
}

Tested the changes with https://github.com/ai/nanoid/tree/v3. I could successfully consume the resulting module from a CJS project with node16 module resolution.

[myftija]

would this be a reasonable assumption?

[myftija]

@ai I noticed that the CI is failing with this error from pnpm: ERR_PNPM_FROZEN_LOCKFILE_WITH_OUTDATED_LOCKFILE. Maybe due to the pnpm version not being pinned in the CI. Would you like me to update the lockfile and add it to this PR? Or are you planning to take care of it in a separate PR?

[ai]

Don't worry, I will fix it. I will take it a few days later.

[ai]

Thanks. Released in 4.0. I will release nanoid 3.x fix soon.