Fix(agentflow): fix duplicate and drag bug and make behavior similar to v2 (#5850)

* Fix duplicate and drag bug

* Fix position of duplicate ndoe to same as v2

* enhance duplicateNode functionality with unique ID generation and position adjustments similar to v2

* enhance deleteNode functionality to clean up connected inputs and remove descendants

* Revert changes to deleteNode

* Modify tests to have a nested structure rather than a flat one

Author: j-sanaa