The CodeDomSerializer does not properly deserialize a CodeTypeReference to a generic type

[aerworker]

Root cause

PR9099

.NET version

8.0.23

Did it work in .NET Framework?

Yes

Did it work in any of the earlier releases of .NET Core or .NET 5+?

7.0.20

Issue description

The CodeDomSerializerBase.GetTypeNameFromCodeTypeReference method returns an incorrect type name for the generic type, e.g. for the nullable int type it returns [[System.Int32, System.Private.CoreLib, Version=8.0.0.0, Culture=neutral, PublicKeyToken=7cec85d7bea7798e]] instead of System.Nullable`1[[System.Int32, System.Private.CoreLib, Version=8.0.0.0, Culture=neutral, PublicKeyToken=7cec85d7bea7798e]]. The subsequent call to the manager.GetType method fails to resolve the string to a type.

Steps to reproduce

Run the following code:

class Program {
    static void Main(string[] args) {
        var serializer = new CodeDomSerializer();
        var expr = new CodeTypeOfExpression(new CodeTypeReference(typeof(long?)));
        var manager = new Manager();
        var result = serializer.Deserialize(manager, expr);
    }
}
class Manager : IDesignerSerializationManager {
    //...
    public object GetService(Type serviceType) {
        if(serviceType == typeof(System.ComponentModel.Design.TypeDescriptionProviderService))
            return null;
        throw new NotImplementedException();
    }

    public Type GetType(string typeName) {
        if(typeName == "System.Int64")
            return typeof(long);
        string expectedTypeName = $"System.Nullable`1[[{typeof(long).AssemblyQualifiedName}]]";
        if(typeName != expectedTypeName)
            throw new Exception("Type name is incorrect");
        else
            return typeof(long?);
    }
    //...
}

[merriemcgaw]

@KlausLoeffelmann - would it be possible to take a look at this issue and the associated PRs?