Make it easier to see widget dimensions from the inspector

Original issue: https://github.com/flutter/flutter-intellij/issues/6759

"Lastly, I'd like to propose the addition of a dedicated tab, preferably positioned between the Layout Explorer and the Widget Details Tree, named 'Dimensions.' It would just display the width and height, providing a simpler view for those who may not require the complex layout details. This was present in the old Flutter Inspector."

首先定位包含 Layout Explorer 和 Widget Details Tree 的 Flutter Inspector UI。确定新的 Dimensions 标签页应如何插入到两者之间，以及如何提供所选 widget 的宽度和高度。完成的标准是 inspector 提供一个更简单的 Dimensions 视图，显示这两个值。

由索引模型根据 Issue 内容生成。