Recreate Directory.build.props from classic Rx in AsyncRx, mostly to enable the latest C#-version but other properties might make sense as well towards a CI build / NuGet-release.

AsyncRx.NET/Directory.build.props

@@ -0,0 +1,38 @@
+<Project>
+  <PropertyGroup>
+    <Copyright>Copyright (c) .NET Foundation and Contributors.</Copyright>
+    <MinClientVersion>2.12</MinClientVersion>
+    <GenerateDocumentationFile>true</GenerateDocumentationFile>
+    <Authors>.NET Foundation and Contributors</Authors>
+    <PackageIconUrl>https://raw.githubusercontent.com/dotnet/reactive/0f837d11385cfaf575861ccc5a5fbcafb22d888f/Rx.NET/Resources/Artwork/Logo.png</PackageIconUrl>
+    <PackageProjectUrl>https://github.com/dotnet/reactive</PackageProjectUrl>
+    <PackageLicenseExpression>MIT</PackageLicenseExpression>
+    <DebugType Condition="'$(Configuration)' != 'Debug'">embedded</DebugType>
+    <SignAssembly>true</SignAssembly>
+    <AssemblyOriginatorKeyFile>$(MSBuildThisFileDirectory)ReactiveX.snk</AssemblyOriginatorKeyFile>
+    <NoWarn>$(NoWarn);1701;1702;CS1591;NU5105</NoWarn>
+    <DefaultLanguage>en-US</DefaultLanguage>
+    <IncludeSymbols>false</IncludeSymbols>
+    <IsTestProject>$(MSBuildProjectName.Contains('Tests'))</IsTestProject>
+    <CodeAnalysisRuleSet>$(MSBuildThisFileDirectory)Rx.ruleset</CodeAnalysisRuleSet>
+    <GeneratePackageOnBuild Condition=" '$(IsTestProject)' != 'true' and '$(CreatePackage)' == 'true' ">true</GeneratePackageOnBuild>
+    <PackageOutputPath>$(MSBuildThisFileDirectory)artifacts</PackageOutputPath>
+    <EmbedUntrackedSources>true</EmbedUntrackedSources>
+    <PublishRepositoryUrl>true</PublishRepositoryUrl>
+    <LangVersion>latest</LangVersion>
+  </PropertyGroup>
+
+  <PropertyGroup Condition="'$(TF_BUILD)' == 'true'">
+    <ContinuousIntegrationBuild>true</ContinuousIntegrationBuild>
+  </PropertyGroup>
+
+  <ItemGroup>
+    <PackageReference Include="Microsoft.SourceLink.GitHub" Version="1.0.0" PrivateAssets="All"/>
+    <PackageReference Include="Nerdbank.GitVersioning" Version="3.2.31" PrivateAssets="all" />
+  </ItemGroup>
+
+  <ItemGroup Condition="'$(IsTestProject)' == 'true'">
+    <PackageReference Include="coverlet.collector" Version="1.3.0" />
+  </ItemGroup>
+
+</Project>