Open Telemetry Support (Cloud Monitoring / Cloud Trace)

**Is your feature request related to a problem? Please describe.**
We would like to use Open Telemetry on GCP but cannot do so easily due to various issues with open telemetry support for dotnet in Google libraries. This has in a tough spot.

- Manually instrument our libraries with the google specific bits knowing fully well that the industry (and google itself) is converging on open telemetry OR
- Standardize on open telemetry and find another sink / backend for our logs.

**Describe the solution you'd like**
Please support open telemetry for the dotnet stack.

**Additional context**
Mixing and matching libraries has not been successful. Even if we use google libraries for logging and open source libraries for traces (exporting to cloud trace), the trace ids don't match up.