Refactoring c# projects (#544)

Small Refactoring c# projects, e.g.
* add days
* remove StartupObject
* Fix Approval tests for NUnit
* Use Environment.NewLine in Xunit tests
* Added + fixed README.md
* Removed global.json

csharp.NUnit/GildedRoseTests/GildedRoseTests.csproj

@@ -1,24 +1,23 @@
 <Project Sdk="Microsoft.NET.Sdk">
 
-    <PropertyGroup>
-        <OutputType>Exe</OutputType>
-        <TargetFramework>net8.0</TargetFramework>
-        <StartupObject>GildedRoseTests.TextTestFixture</StartupObject>
-    </PropertyGroup>
+  <PropertyGroup>
+    <OutputType>Exe</OutputType>
+    <TargetFramework>net8.0</TargetFramework>
+  </PropertyGroup>
 
-    <ItemGroup>
-        <PackageReference Include="Verify.NUnit" Version="23.1.0" />
-        <PackageReference Include="Microsoft.NET.Test.Sdk" Version="17.8.0" />
-        <PackageReference Include="NUnit" Version="4.0.1" />
-        <PackageReference Include="coverlet.collector" Version="6.0.0">
-            <IncludeAssets>runtime; build; native; contentfiles; analyzers; buildtransitive</IncludeAssets>
-            <PrivateAssets>all</PrivateAssets>
-        </PackageReference>
-        <PackageReference Include="NUnit3TestAdapter" Version="4.5.0" />
-    </ItemGroup>
+  <ItemGroup>
+    <PackageReference Include="Verify.NUnit" Version="23.1.0" />
+    <PackageReference Include="Microsoft.NET.Test.Sdk" Version="17.8.0" />
+    <PackageReference Include="NUnit" Version="4.0.1" />
+    <PackageReference Include="coverlet.collector" Version="6.0.0">
+      <IncludeAssets>runtime; build; native; contentfiles; analyzers; buildtransitive</IncludeAssets>
+      <PrivateAssets>all</PrivateAssets>
+    </PackageReference>
+    <PackageReference Include="NUnit3TestAdapter" Version="4.5.0" />
+  </ItemGroup>
 
-    <ItemGroup>
-        <ProjectReference Include="..\GildedRose\GildedRose.csproj" />
-    </ItemGroup>
+  <ItemGroup>
+    <ProjectReference Include="..\GildedRose\GildedRose.csproj" />
+  </ItemGroup>
 
 </Project>