Handler key on the parent UdsTester (e.g. 'someipApi', 'serialPortApi', 'output').
Inner payload forwarded to that handler (the worker automatically assigns payload.id from
global.cmdId before incrementing it).
Promise settled when the parent calls __eventDone with the same id, or rejected if the parent reports err.
Typical pattern:
emitWorkerEventWithReply('someipApi', { op: 'request', msg: { ... } })
Submodule someip.ts uses a lazy require('./uds') + this helper to avoid circular static imports while still
participating in the same emitMap lifecycle as output.
Emit a worker event that expects a single correlated completion from the main process.