Fix linux style slashes in dotnet build, use dotnet test over appveyor xunit

Author: jimschubert

appveyor.yml

@@ -25,8 +25,8 @@ install:
 build_script:
   - dotnet --info
   # build C# API client (refactor)
-  - dotnet build samples/client/petstore/csharp-refactor/OpenAPIClient/Org.OpenAPITools.sln
-  - dotnet build samples/client/petstore/csharp-refactor/OpenAPIClientCore/Org.OpenAPITools.sln
+  - dotnet build samples\client\petstore\csharp-refactor\OpenAPIClient\Org.OpenAPITools.sln
+  - dotnet build samples\client\petstore\csharp-refactor\OpenAPIClientCore\Org.OpenAPITools.sln
   # build C# API client
   - nuget restore samples\client\petstore\csharp\OpenAPIClient\Org.OpenAPITools.sln
   - msbuild samples\client\petstore\csharp\OpenAPIClient\Org.OpenAPITools.sln /logger:"C:\Program Files\AppVeyor\BuildAgent\Appveyor.MSBuildLogger.dll"
@@ -42,8 +42,8 @@ test_script:
   # restore test-related files
   - copy /b/v/y CI\samples.ci\client\petstore\csharp\OpenAPIClient\src\Org.OpenAPITools.Test\Org.OpenAPITools.Test.csproj samples\client\petstore\csharp\OpenAPIClient\src\Org.OpenAPITools.Test\Org.OpenAPITools.Test.csproj
   # test c# API client (refactor)
-  - '%xunit20%\xunit.console samples\client\petstore\csharp-refactor\OpenAPIClient\src\Org.OpenAPITools.Test\bin\Debug\netcoreapp2.0\Org.OpenAPITools.Test.dll -appveyor'
-  - '%xunit20%\xunit.console samples\client\petstore\csharp-refactor\OpenAPIClientCore\src\Org.OpenAPITools.Test\bin\Debug\netcoreapp2.0\Org.OpenAPITools.Test.dll -appveyor'
+  - dotnet test samples\client\petstore\csharp-refactor\OpenAPIClient\src\Org.OpenAPITools.Test\Org.OpenAPITools.Test.csproj
+  - dotnet test samples\client\petstore\csharp-refactor\OpenAPIClientCore\src\Org.OpenAPITools.Test\Org.OpenAPITools.Test.csproj
   # test c# API client
   - nunit-console samples\client\petstore\csharp\OpenAPIClient\src\Org.OpenAPITools.Test\bin\Debug\Org.OpenAPITools.Test.dll --result=myresults.xml;format=AppVeyor
   # test c# API client (with PropertyChanged)