Introduce NPM Package Functionality and Enhancements to Document Conversion API

[HlexNC]

This PR introduces several key enhancements and additions to the Document Conversion API, aligning with our goal to expand the API's capabilities and ease of use. Below is a summary of the changes:

• NPM Package Introduction: The API has been structured as an NPM package, facilitating easier integration into JavaScript and Node.js projects. This update includes necessary package.json adjustments and dependency updates.

• New Documentation and Examples: To assist developers in leveraging the new NPM package, we've added comprehensive examples (api-usage.md and library-usage.md). These documents guide through the API utilization and library functions, demonstrating practical use cases.

• API and Utility Enhancements: Updates to app.js and officegenHelper.js include improvements in API endpoint structures and the document generation utility, optimizing performance and expanding the feature set.

• Workflow Adjustments for NPM Publishing: Modifications to .github/workflows/publish.yml ensure seamless integration with GitHub Actions for automated NPM package publishing, enhancing our CI/CD pipeline.

• Addition of documentLibrary.js: A new library file introduces advanced document handling capabilities, further broadening the API's utility for complex document generation and manipulation tasks.

Conclusion:

This PR sets the stage for a more integrated and developer-friendly Document Conversion API. By embracing NPM packaging, we not only streamline the usage process but also open up new avenues for application development. We encourage feedback on these changes as we continue to enhance the API's functionality.