Implement OpenTracing shim

[reyang]

Refer to https://github.com/open-telemetry/opentelemetry-python/tree/v1.10.0/shim/opentelemetry-opentracing-shim.

[github-actions]

This issue was marked as stale due to lack of activity. It will be closed in 7 days if no furthur activity occurs.

[chalin]

Consider changing "bridge" to "shim" in the title (since the terminology has changed since this issue was created).

[lalitb]

Consider changing "bridge" to "shim" in the title (since the terminology has changed since this issue was created).

Thanks, done.