[C#][netcore] auto-generate appveyor.yml (#7212)

* auto-generate appveyor.yml

* Update modules/openapi-generator/src/main/resources/csharp-netcore/appveyor.mustache

Co-authored-by: Tatsuro Shibamura <me@shibayan.jp>

* Update modules/openapi-generator/src/main/resources/csharp-netcore/appveyor.mustache

Co-authored-by: Tatsuro Shibamura <me@shibayan.jp>

* Update modules/openapi-generator/src/main/resources/csharp-netcore/appveyor.mustache

Co-authored-by: Tatsuro Shibamura <me@shibayan.jp>

* Update modules/openapi-generator/src/main/resources/csharp-netcore/appveyor.mustache

Co-authored-by: Tatsuro Shibamura <me@shibayan.jp>

* update samples

Co-authored-by: Tatsuro Shibamura <me@shibayan.jp>

samples/client/petstore/csharp-netcore/OpenAPIClient/.openapi-generator/FILES

@@ -1,6 +1,7 @@
 .gitignore
 Org.OpenAPITools.sln
 README.md
+appveyor.yml
 docs/AdditionalPropertiesClass.md
 docs/Animal.md
 docs/AnotherFakeApi.md

samples/client/petstore/csharp-netcore/OpenAPIClient/appveyor.yml

@@ -0,0 +1,9 @@
+# auto-generated by OpenAPI Generator (https://github.com/OpenAPITools/openapi-generator)
+#
+image: Visual Studio 2019
+clone_depth: 1
+build_script:
+- dotnet build -c Release
+- dotnet test -c Release
+after_build:
+- dotnet pack .\src\Org.OpenAPITools\Org.OpenAPITools.csproj -o ../../output -c Release --no-build

samples/client/petstore/csharp-netcore/OpenAPIClientCore/.openapi-generator/FILES

@@ -1,6 +1,7 @@
 .gitignore
 Org.OpenAPITools.sln
 README.md
+appveyor.yml
 docs/AdditionalPropertiesClass.md
 docs/Animal.md
 docs/AnotherFakeApi.md

samples/client/petstore/csharp-netcore/OpenAPIClientCore/appveyor.yml

@@ -0,0 +1,9 @@
+# auto-generated by OpenAPI Generator (https://github.com/OpenAPITools/openapi-generator)
+#
+image: Visual Studio 2019
+clone_depth: 1
+build_script:
+- dotnet build -c Release
+- dotnet test -c Release
+after_build:
+- dotnet pack .\src\Org.OpenAPITools\Org.OpenAPITools.csproj -o ../../output -c Release --no-build