[Property editor] Value dropdown style feedback

### Context

In the Property Editor, enum and boolean values get a dropdown:


### Suggestions

When I open the dropdown, its items cover the dropdown. It makes it hard to know what I’m editing. Can we make the dropdown items show below the dropdown?

The dropdown items’ width is wider than the width of the collapsed dropdown itself. Ideally their widths would be the same.

I dislike the Material ink splash effect when you click on these dropdown items. It feels jarring and inconsistent with VS Code’s UX. Can we turn off Material ink splash effects?

首先定位 Property Editor 的实现以及渲染 enum 和 boolean 下拉菜单的代码。在 Property Editor 中重现该反馈，然后验证菜单项是否显示在字段下方、与字段宽度一致，并且不显示 Material 的墨水飞溅效果。

由索引模型根据 Issue 内容生成。