Add support for both ES modules and Common JS

[Yang-33]

Summary

As the JavaScript ecosystem continues to evolve, ES Modules (ESM) have become a standard for modern development, offering benefits such as improved loading performance and better tooling support. To align with these advancements and increase the library's usability across various environments, I propose adding support for ES Modules.

Motivation

Adding ESM support would make line/line-bot-sdk-nodejs more versatile and accessible for developers working in both Node.js and compatible environments. It would also facilitate smoother integration with modern build tools and enable tree-shaking for more efficient bundling.

[Yang-33]

Task lists

• Stop reading package.json from sdk code #792
• Use Vitest instead of Mocha #793
• Support only ESM at first #794
• Add an example with Typescript and ESM #795
• Support CJS again #797
• Fix typescript with cjs compile issue #802
• Update example and document for ESM #810
• Do not publish tests #803

[Yang-33]

These changes are in v9.1.0!