Add OTLP Logs support

[cartermp]

Since we support them on our endpoint!

[cartermp]

Note: this would require taking a dependency on this package (for now?) - https://www.nuget.org/packages/OpenTelemetry.Exporter.OpenTelemetryProtocol.Logs/1.4.0-alpha.2

[cartermp]

https://github.com/open-telemetry/opentelemetry-dotnet/tree/main/src/OpenTelemetry.Exporter.OpenTelemetryProtocol#otlp-logs

[cartermp]

I did a quick spike on this and it's pretty easy to add. That said, I think, given that there's a lot more churn in the upstream SDK, we should only add it as a part of our AddHoneycomb call and not expose public extensions to ILoggerBuilder. My reasons:

1. I think it is likely that they may also include a LoggerProviderBuilder type that you're expected to extend and add your own logger to
2. Serilog is so widely-used that they may even just add a sink to the project and let you configure it
3. API churn in general

Rather than ship extensions to a thing that may undergo churn, we should make it internal for now and no expose any API for people to call. I still think it's valuable to add logs support, so let's not let this deter us from adding them. Lots of folks use the microsoft logging framework and could benefit from having those logs "just work" when honeycomb is added.

[cartermp]

@MikeGoldsmith and I chatted and think that this should probably get punted, or at least just done orthogonally to the release. The issue is that it requires pulling in prerelease packages, which we can't do if we want to make our distro actually GA. We can build a honeycomb logging exporter package and release it separately for now.