trace: add Random Trace ID Flag#8012

dmathieu merged 8 commits intoopen-telemetry:mainopen-telemetry/opentelemetry-go:mainfrom

yuanyuanzhao3:support-w3c-sampled-random-flagsyuanyuanzhao3/opentelemetry-go:support-w3c-sampled-random-flagsCopy head branch name to clipboard