[FFI/JNI Refactor]: Scope sync e.g user/contexts/extras/tags/breadcrumbs

### Description

Migrate the following methods to direct native calls: 
- `addBreadcrumb`, `clearBreadcrumbs`: https://github.com/getsentry/sentry-dart/issues/3204
- `setContexts`, `removeContexts`
- `setExtra`, `removeExtra`
- `setTag`, `removeTag`
- `setUser`