Azure Pipelines build and release pipeline

At present, we have a mix of build systems that I would like to unify.

1. Azure Pipelines for Linux, Windows and macOS.
2. Travis for Linux and macOS
3. Appveyor for Windows

I'd like to standardize around Azure Pipelines. At the moment, it's only doing a build for validation. I would like the build step to:

1. Create a nuget package (see AppVeyor's build configuration)
2. Upload that nuget package to Azure Artifacts

Then I'd like to have a separate release pipeline that will:

1. Take the nuget package from Azure Artifacts
2. Upload the nuget package to nuget.org

从现有的 Azure Pipelines 验证构建和 AppVeyor 的构建配置开始，它们是 issue 中指定的入口点。跟踪 NuGet 包的创建方式，并确定发布到 Azure Artifacts 和 nuget.org 的步骤。完成的标准是 Azure Pipelines 构建并存储该包，同时由单独的 release pipeline 将其发布到 nuget.org。