Add support for non-stream response with session.ask_without_stream and
fix a typo mistake in python API doc
There are requirements for non-stream response, especially for commands
exection, e.g. text2SQL. The commands have to be completed before the
agent is triggered.

### What problem does this PR solve?

It's to fix the [Issue:
6206](https://github.com/infiniflow/ragflow/issues/6206)

### Type of change

- [x] Bug Fix (non-breaking change which fixes an issue)
- [ ] New Feature (non-breaking change which adds functionality)
- [ ] Documentation Update
- [ ] Refactoring
- [ ] Performance Improvement
- [ ] Other (please describe):

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Co-authored-by: Howard WU <yuanhao.wu@ifudata.com>
Co-authored-by: Kevin Hu <kevinhu.sh@gmail.com>