Extension modules - update MSVC for standalone module

The page https://devguide.python.org/developer-workflow/extension-modules/#updating-msvc-project-files has recently been updated with fantastic content.

However, it currently only shows how to add a built-in module for Windows, and not a separate extension module.

We should add a second section that adds a new .vcxproj for the new extension module (or more likely copies a recommended existing one), along with the other changes necessary to ensure the new module is correctly built and distributed.

從 issue 中連結的開發者工作流程頁面的「Updating MSVC project files」區段開始。記錄為獨立擴充模組建立或複製 .vcxproj 的其他步驟，包括建置和散佈方面的變更；當頁面涵蓋內建擴充模組和獨立擴充模組時即完成。