Fix S3925 FP: Classes not having extra properties should not have to extend ISerializable interface

[Corniel]

Description

Rule S3925 demands that classes should always override ISerializable methods. However, if the class has no extra properties (or fields) this is not necessary, like in this scenario:

public CustomLookup : Dictionary<string, object> // Compliant, no extra fields/properties to serialize
{
}

The rule should not be applied in cases like these.

[martin-strecker-sonarsource]

According to the RSpec, this is indeed a false positive:

• A derived type has serializable fields but the ISerializable.GetObjectData method is not overridden.

[martin-strecker-sonarsource]

@Corniel This issue was closed as part of our work at #7721. This issue is slightly different, but I don't think it is needed anymore as it should cover the changes we made. If you still think that there are FPs, feel free to re-open or raise a new issue.
Thank you anyway for bringing this up and for your work on #5709 It helped a lot to improve the rule 👍 .

[Corniel]

I think this solution should also work.