constructor(segment, transaction) {
    this.segmentId = segment.id
    this.traceId = transaction.traceId
  }
In order to be able to return the appropriate span context
within otel bridge. We have to create fake spans for new relic
segments.  The only thing needed is a method for `spanContext`
which should return the spanId(segment id) and traceId(transaction trace id).
We hardcode traceFlags to 1.