stop method
Stops playing sound identified by streamId
Implementation
Future<void> stop(int streamId) async {
assert(!_disposed, "Soundpool instance was already disposed");
assert(streamId > 0,
"Invalid 'streamId' parameter. Only values greater than 0 are valid.");
int poolId = await _soundpoolId.future;
await _platformInstance.stop(poolId, streamId);
}