frontend: Add optional sampling of GraphQL requests in Honeycomb
Created by: ryanslade
We optionally sample the following data for GraphQL requests:
- Query
- Query cost estimate
- Query cost version, so that we can tweak the algorithm
- Whether the user is anonymous
- GraphQL operation name
- Was the request was handled by our internal or external handler
Closes: https://github.com/sourcegraph/sourcegraph/issues/18099