Office Add-in Test Helpers

The `office-addin-test-helpers` package provides essential utilities for automating the validation and testing of Office Add-ins. Part of the broader `Office-Addin-Scripts` monorepo maintained by Microsoft OfficeDev, this library offers programmatic access to functionalities like manifest verification, add-in registration, sideloading, and communication with a test server. It is commonly used in conjunction with the `office-addin-test-server` package and popular testing frameworks such as Mocha or Jest to facilitate integration and end-to-end testing of add-ins across various Office applications (Excel, Word, Outlook, etc.). The current stable version is 2.0.4. While the monorepo has different release cadences for its constituent packages, `office-addin-test-helpers` generally follows a steady update schedule, ensuring compatibility with the evolving Office Add-ins platform.