Remove label gap in treemap

Hello. I have been finding plotly's treemaps very useful

One feature that I would find helpful is being able to remove the gap below each box label.

The problem is that for smaller boxes, the gap ends up taking a large amount of the space. This space is essentially wasted, and it makes each node's children proportionally smaller than they otherwise would be. This prevents an accurate visual comparison between one parent's children to another parent's children.

I have highlighted what I mean in the figure below using red arrows

Charts with lots of nesting would benefit a lot from being able to use this space

该 issue 没有指明实现文件或测试。首先定位 treemap 的入口点以及现有的 layout 或 rendering 测试，然后比较有无标签间距时的嵌套框。完成后应提供一种移除该间距的方法，使子区域更大，同时在视觉上保持比例可比。