Add a central `SentryWidget`

[buenaflor]

Description

Let's explore the possibility to add a central SentryWidget that allows to enable/disable features of other widgets such as SentryScreenshotWidget etc... so we avoid causing a nested Widget structure for the user.

This also helps in eliminating the need for adding new widgets for cases such as #1832 since we could potentially just add it to the SentryWidget

[buenaflor]

  Widget build(BuildContext context) {
    Widget content = widget.child;
    content = SentryScreenshotWidget(child: content);
    content = SentryUserInteractionWidget(child: content);
    // ... add more relevant widgets
    return content;
  }

// and the user only needs to do:
SentryWidget(child ...);

doing something like this works fine, we prolly should get the flutter options to conditionally add the widgets to reduce overhead for unused widgets