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)