自定义流程图能否收缩节点？ #3328

• I have searched the issues of this repository and believe that this is not a duplicate.

What problem does this feature solve?

避免全流程节点太多影响视觉

What does the proposed API look like?

全流程图，多节点，有开始节点和结束节点，中间的那些节点可收缩

<!-- generated by antv-issue-helper. DO NOT REMOVE -->