Consider adding DiagnosticSource support

[ejsmith]

https://github.com/dotnet/runtime/blob/master/src/libraries/System.Diagnostics.DiagnosticSource/src/DiagnosticSourceUsersGuide.md

https://github.com/dotnet/runtime/blob/master/src/libraries/System.Diagnostics.DiagnosticSource/src/ActivityUserGuide.md

https://github.com/microsoft/ApplicationInsights-dotnet/blob/develop/WEB/LibraryInstrumentationGuidance.md

https://docs.microsoft.com/en-us/aspnet/core/fundamentals/logging/loggermessage?view=aspnetcore-3.1

https://github.com/grpc/grpc-dotnet/blob/57fa08534b834c70c2540fa24f1d23f18794f15e/src/Grpc.Net.Client/Internal/GrpcCall.cs#L661

[ejsmith]

I added support for tracking correlationid through on queue entries and then did an experiment to make sure that you can add activities and diagnostics for queue entry processing outside of Foundatio. That works. Not sure if we want to take a dependency on System.Diagnostics.DiagnosticSource. I've heard some other people have had trouble with taking on that dependency probably because of the same diamond dependency issue that we have had with JSON.NET and other common libs. I really like that our base nuget package doesn't have a lot of dependencies. We did recently take on a System.Text.Json dependency and that seems like it would be the same issue, but I think the plan there is that hopefully that gets moved into .net standard. Not really sure what is going to happen with .net 5. I heard something about .net standard might be going away somehow.

[ejsmith]

open-telemetry/opentelemetry-dotnet#506