feat: support cjs & esm

[schulzf]

Add Support for CommonJS via ESM & CJS Builds

Summary

This pull request implements dual builds for the SuperJSON library, adding support for both ECMAScript Modules (ESM) and CommonJS modules (CJS). This enhancement ensures compatibility with various JavaScript environments and module loaders, particularly focusing on improving integration with the NestJS framework.

Changes

• Configured build scripts to generate both ESM and CJS outputs.
• Updated package.json to point to the correct module formats:
  • "main" field now points to the CJS build.
  • "module" field now points to the ESM build.

Motivation

This enhancement aims to facilitate seamless integration with the NestJS framework, which benefits from CommonJS module support.

Testing

• Verified that the ESM build works correctly by importing the library in a project using ESM syntax.
• Verified that the CJS build works correctly by requiring the library in a project using CJS syntax.
• Updated existing unit tests to run against both module formats to ensure consistent behavior.

Please review the changes and provide any feedback. Thank you!

[Skn0tt]

Hi Felipe! Thanks for going ahead and opening this PR, but this is not the kind of contribution that's fit for a drive-by PR. Moving to ESM-only was a conscious decision, and there's enough workarounds for using SuperJSON from CommonJS. I appreciate your effort though!