Configure output path for "dotnet pack"

.gitignore

@@ -3,3 +3,4 @@ bin/
 obj/
 *.user
 launchSettings.json
+artifacts/

Directory.Build.props

@@ -7,6 +7,7 @@
     <RepositoryType>git</RepositoryType>
     <RepositoryRoot>$(MSBuildThisFileDirectory)</RepositoryRoot>
     <TreatWarningsAsErrors>true</TreatWarningsAsErrors>
+    <PackageOutputPath>$(MSBuildThisFileDirectory)artifacts\build</PackageOutputPath>
   </PropertyGroup>
 
   <PropertyGroup>