Use dot-shorthand syntax for doubles when possible

If a user has a double property that could support dot shorthand syntax but isn't, e.g.:

* `double.infinity` -> `.infinity`
* `double.nan` -> `.nan`

We could display the dot-shorthand version to help users discover this new language feature. This would require the analysis server to send the current Dart version to the Property Editor Client so that the Property Editor Client can determine whether dot-shorthand syntax is supported.

追踪 analysis server 如何与 Property Editor Client 通信，并确定可以在哪里提供当前的 Dart 版本。然后检查属性显示逻辑中对 double.infinity 和 double.nan 等情况的处理，并验证只有在受支持的语言版本允许时才显示点号简写。

由索引模型根据 Issue 内容生成。