feat(types): Add threads to Event

[krystofwoldrich]

Implements nonbreaking changes from

• fix(event): Move stack trace from exception to threads for message events #6038

this way RN can patch the behavior in its next major release.

The RN patch

• fix(event): Message event includes current stack trace in threads sentry-react-native#2694

[AbhiPrasad]

https://develop.sentry.dev/sdk/event-payloads/threads/

[krystofwoldrich]

Thanks.