Minimize telemetry surface area

[davidmrdavid]

Under certain conditions (user opting in to tracing raw inputs and outputs), our telemetry may capture sensitive information. For example, through logs of exceptions, inputs, output, etc. T

This PR aims to remove the sensitive information by implementing these guidelines:

(1) User-provided inputs and outputs are never part of telemetry as-is. This includes the "reason" label for operations like terminate or rewind, as well as the simpler cases of inputs and outputs to orchestrators and entities.

(2) When application-level exceptions are logged, we only log a sanitized version of them that includes the exception type, and the exception stack trace. The exception message is absent, as it may contain sensitive information.

And that's it. To this end, I've refactored many methods in the EndToEndTracer class, as well as their callers. In most cases, the refactoring is simply to avoid logging sensitive parameters via ETW, but still logging them to the user's Application Insights.

The more complicated refactorings are all around logging exceptions. In the easy case - I simply refactored the string parameter containing the exception string into an actual Exception type, that I can use to create a sanitized exception string containing only the exception type and stack trace. Other cases where the exception object wasn't available in the immediate caller are handled on a case-by-case basis.

Finally - some diffs in this PR are minor improvements like adding nullable analysis and removing build warnings.

resolves N/A

Pull request checklist

• [x] My changes do not require documentation changes
  • [ ] Otherwise: Documentation PR is ready to merge and referenced in pending_docs.md
• [x] My changes should not be added to the release notes for the next release
  • [ ] Otherwise: I've added my notes to release_notes.md
• [x] My changes do not need to be backported to a previous version
  • [ ] Otherwise: Backport tracked by issue/PR #issue_or_pr
• [x] I have added all required tests (Unit tests, E2E tests)
• [x] My changes do not require any extra work to be leveraged by OutOfProc SDKs
  • [ ] Otherwise: That work is being tracked here: #issue_or_pr_in_each_sdk
• [ ] My changes do not change the version of the WebJobs.Extensions.DurableTask package
  • [ ] Otherwise: major or minor version updates are reflected in /src/Worker.Extensions.DurableTask/AssemblyInfo.cs
• [x] My changes do not add EventIds to our EventSource logs
  • [ ] Otherwise: Ensure the EventIds are within the supported range in our existing Windows infrastructure. You may validate this with a deployed app's telemetry. You may also extend the range by completing a PR such as this one.
• [x] My changes should be added to v3.x branch.
  • [ ] Otherwise: This change only applies to Durable Functions v2.x and will not be merged to branch v3.x.

[davidmrdavid]

Just realized a bunch of logging unit tests broke, which is good, but it means I need to update them. Still, I'd appreciate a quick pass on the proposed refactoring in the meantime. Thanks

[davidmrdavid]

Tests are passing. I'd appreciate a review here, @cgillum. Thanks!