ITs: update Net5 test cases

[zsolt-kolbay-sonarsource]

Some of the .NET test cases are not up to date. e.g. Module Initializers were introduced in C# 9.0, but currently analyzers/its/sources/Net5/Net5/ModuleInitializers.cs looks like this:

namespace Net5
{
    public class ModuleInitializers
    {
        // The feature is in progress

        //[ModuleInitializer]
        //internal static void Initializer()
        //{
        //}
    }
}

All test cases under the Net5 folder (as well as Net6, and Net7) in analyzers/its/sources need to be double-checked and updated if necessary.

[pavel-mikula-sonarsource]

@zsolt-kolbay-sonarsource Can you please clarify the title of this card? The example resembles a project from our ITs only, the title suggest our UTs/TestCases.

Only Type: Tooling label is relevant here. This doesn't affect rules or any specific C# version of a rule.