Sync User and Session data between Android/iOS SDKs and WebSDK

### Problem Statement

In our apps we are using WebViews to provide some features dynamically.
As we are using Sentry in Web and App, we would love to be able to sync the user and session data between the Web and Native SDKs.

### Solution Brainstorm

It would be awesome if Sentry would provide some kind of JS bridge or other way of syncing the data between the SDKs in WebViews.

┆Issue is synchronized with this [Jira Improvement](https://getsentry.atlassian.net/browse/FEEDBACK-1953) by [Unito](https://www.unito.io)

該 issue 未指明檔案、測試或進入點。首先定位 Android/iOS WebView 整合和 WebSDK bridge 選項，然後定義使用者資料和工作階段資料應如何在各 SDK 之間流動；當形成一致同意的整合設計，並在受支援的平台之間同步這兩類資料時，即視為完成。

由索引模型根據 Issue 內容生成。