Add support for local scopes

Allow capturing events with local scopes as in other Sentry SDKs.

Documentation:
- [Scopes in dev docs](https://develop.sentry.dev/sdk/telemetry/scopes/).
- [Scopes in Javascript](https://docs.sentry.io/platforms/javascript/enriching-events/scopes/).

Depends on:
- https://github.com/getsentry/sentry-native/issues/1226
- https://github.com/getsentry/sentry-native/pull/1248
