[Enhancement] Workflow Feature Implementation: Support task result output

### Search before asking

- [X] I had searched in the [issues](https://github.com/apache/eventmesh/issues?q=is%3Aissue) and found no similar issues.

### Enhancement Request

Support task result output

### Describe the solution you'd like

add output field, same as input, based on EM

### Are you willing to submit PR?

- [ ] Yes I am willing to submit a PR!

The issue names no files, tests, or entry points. Start by locating the existing workflow task input handling in EventMesh and clarify what “based on EM” means; done should be defined as a specified output field with coverage for task results.

Written by the indexing model from the issue text.