[Feature Request] View masking previews

### Problem Statement

I am integrating Session Replay in a React native based app with some custom masking rules. Each time I need to check how the view is masked, I have to run the app, wait for the session to appear on sentry, scroll the video to find my target screen and finally check the masking. Repeat until I've got it right.

This is very tedious to do and is error-prone.

### Solution Brainstorm

Add a `SentryMaskPreview` component that can be used to render a masked child component. We can then rely on hot-reload to get a quick feedback loop when implementing custom masking logic.

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The iOS native feature request:
[https://github.com/getsentry/sentry-cocoa/issues/4633]()

该 issue 未指明文件、测试或入口点。首先查看链接的 sentry-cocoa 请求，以及现有的 React Native masking 和 Session Replay 实现；完成的标准是提供一个 SentryMaskPreview 组件，用于渲染经过 masking 的 child，并支持通过 hot reload 实现快速反馈循环。

由索引模型根据 Issue 内容生成。