TimespanLogging: Provide log serialization helper

[jpsamaroo]

It's super common to want to export logs to a file to be later imported for analysis. We could provide an interface to export to any Tables.jl-compatible sink to make this easy.

An open question is how to serialize streams of a MultiEventLog, which tend to have different formats. These also often contain data like Dict or NamedTuple which don't serialize nicely as column values in CSV; maybe we should also have a JSON-based format? If we emit JSON, we could also move most of the sanitization code from DaggerWebDash over to TimespanLogging.

[findmyway]

Hi @jpsamaroo ,

I'm working on oolong-dev/OpenTelemetry.jl#74 recently. I believe most logging related issues listed here can be addressed gracefully. Maybe we can have a discussion on it in the next Dagger.jl user meeting?

[jpsamaroo]

@findmyway sounds great to me!