feat(csharp): add PII redaction in tracing, by default

[birschick-bq]

Adds PII redaction in tracing, by default.

The new class ActivityWithPii wraps the System.Diagnostics.Activity object and replicates its interface. By default, the methods assume that tag values passed to the methods contain PII, unless explicitly marked otherwise (i.e., isPii = false).

The previous TraceActivity overloads and extension method that are use Activity have been marked as Obsolete. They have been replaced with overloads using the new ActivityWithPii class.

As marking the TraceActivity overloads and extension methods as Obsolete causes the build to fail, I've update the drivers in two commits. The first commit uses #pragma to ignore the warnings. The second commit, implements the change to use the new ActivityWithPii class.

The FileExporter and FileListener have been updated to reveal the original that have been redacted - with the assumption that writing to the local file system is controlled by an authorized user.

[birschick-bq]

@CurtHagenlocher - let me know if you have some time to review this or if is a low priority for you. Thanks.

[davidhcoe]

I think we can remove the changes that are under the Drivers folder since those are on the deprecation path. The changes are only needed in the new Foundry repo.

[davidhcoe]

I think we can remove the changes that are under the Drivers folder since those are on the deprecation path. The changes are only needed in the new Foundry repo.

I see. You mention in the description the build was breaking without that.

[birschick-bq]

I think we can remove the changes that are under the Drivers folder since those are on the deprecation path. The changes are only needed in the new Foundry repo.

I see. You mention in the description the build was breaking without that.

I could remove the Obsolete attributes, now that I've found all references. Then add back the Obsolete attribute once the other files are deprecated driver files and removed.

[davidhcoe]

Yes lets do that.