feat: AWEL flow supports dynamic parameters

[fangyinc]

Description

AWEL flow dynamically read optional parameter list, now supports:

• SpaceRetrieverOperator
• AwelAgent

How Has This Been Tested?

Test it with SpaceRetrieverOperator.

1. Start DB-GPT
2. New AWEL flow, select SpaceRetrieverOperator, you can see a list of "Space Name"
3. Create a new knowledge space.
4. Reload your web page.
5. New AWEL flow, select SpaceRetrieverOperator, you can see a list of "Space Name" includs your new space name.

Snapshots:

Include snapshots for easier review.

Checklist:

• My code follows the style guidelines of this project
• I have already rebased the commits and make the commit message conform to the project standard.
• I have performed a self-review of my own code
• I have commented my code, particularly in hard-to-understand areas
• I have made corresponding changes to the documentation
• Any dependent changes have been merged and published in downstream modules

[yhjun1026]

r+

[Aries-ckt]

LGTM!