Add onCrashedLastRun

[philipphofmann]

Add a callback onCrashedLastRun to SentryOptions that is called by the SDK passing the event
when Sentry is initialized and the last program execution terminated with a crash.

PR in Cocoa: getsentry/sentry-cocoa#808
Docs in Cocoa: https://docs.sentry.io/platforms/apple/enriching-events/user-feedback/
The issue on Java: getsentry/sentry-java#1125

[dalux-era]

Hi.
Could this feature get a prioritization bump? A lot of people are switching from AppCenter to Sentry. It would definitely help migrating for all the .NET projects that had this feature in AppCenter - Crashes.HasCrashedInLastSessionAsync().