Enable export from CPU Profiler.

I am analyzing CPU profile and I would like to search by some words. For example, to highlight frames from certain library.

It would be great to be able to export what i see in some text or csv format so that I can analyse and may be annotate it in spreadsheets or text editor.

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**DevTools version**: 2.31.0
**Connected Device**:
CPU / OS: arm64 (64 bit) macos
Connected app type: Flutter native (debug build)
Dart Version: 3.4.0-24.0.dev
Flutter Version: 3.19.0-6.0.pre.18 / master
Framework / Engine: 0503c44718 / d4b6b7ec8e

从 CPU Profiler 视图开始，确定显示的 profile 数据是如何组装的。确定导出操作如何以文本或 CSV 的形式提供可见数据，以便在电子表格或文本编辑器中进行分析。用户能够以可用格式导出 CPU profile 数据即视为完成。

由索引模型根据 Issue 内容生成。