Allow for interface implementations in EventSource.WriteEventVarArgs (dotnet/coreclr#25844)
* Allow for interface implementations in EventSource.WriteEventVarArgs
* Also account null ref types and nullable types
* fix error in comment and simplify first part of boolean logic
* Update src/System.Private.CoreLib/shared/System/Diagnostics/Tracing/EventSource.cs
Co-Authored-By: Noah Falk <noahfalk@users.noreply.github.com>
Commit migrated from https://github.com/dotnet/coreclr/commit/
c284bbfa83db019c34afe8835e198409f4168c02