Document PythonTest and PythonEmbed install options

We should add to Docs/using/windows.rst some mention that CPython is available as PythonCore/, PythonTest/ and PythonEmbed/ variants, with a summary of what each contains.

It needs to be phrased carefully to make it clear that these are choices made when publishing CPython, not inherent features of PyManager. The only inherent part is that PythonCore is the default company.

Linked PRs

• gh-154482

更新 Docs/using/windows.rst。首先檢閱有關 PyManager 與 CPython 發佈的相關文件，然後描述 PythonCore、PythonTest 和 PythonEmbed 變體，以及每個變體包含的內容。明確說明這些選項由發佈者選擇，而 PythonCore 是預設公司；當這些差異和預設值都獲得準確記錄時，即表示完成。