Provide way of only unregister specific instance of WebView

[JohannesPtaszyk]

Hello,

we are currently facing an issue while having multiple WebViews on different Screens inside our compose app.
It might occur sometimes, that we navigate through the app and call unregister() on the AdjustBridge, to clean up the WebView when leaving a screen. But in some cases it occurs that a new WebView was already active and registered at that point, so we should not unregister the new instance, but as the unregister is called slightly after the new one was registered, we have a fuckup.

It would be great if we could either have support for registering and unregistering multiple WebView instances OR if we could pass a WebView instance to the unrigster() (Maybe just an overload which takes the parameter) and then only execute the unregister code, if the instance is the same one as the currently attached one.