internal/trace: extract trace policy to OT-agnostic package
Created by: bobheadxi
This change extracts generic "should we trace" logic into a new package, trace/policy
, in an effort to disentangle from OpenTracing and migrate to the OpenTelemetry package. No logic changes, just code moves.
Part of https://github.com/sourcegraph/sourcegraph/issues/27386
Test plan
Tests pass