Map iOS Native BeforeSend & OnCrashedLastEvent to SentryOptions.Native

[aritchie]

Resolves #2102

[aritchie]

@jamescrosswell @bruno-garcia Native exceptions obviously teardown the MAUI apps. I can't unit test this properly due to needing to shutdown the app. Thoughts? Any internal mechanism I can call in native to have it "pretend" an issue occurred previously and force run BeforeSend/CrashedLastRun

[bitsandfoxes]

Over at https://github.com/getsentry/sentry-unity/ we're covering this via smoketests which to me seems more reliable to guarantee native-crash capture.
Two runs:

1. Running and crashing on purpose
2. Running again and expecting the crashedLastRun to be true

[jamescrosswell]

@jamescrosswell @bruno-garcia Native exceptions obviously teardown the MAUI apps. I can't unit test this properly due to needing to shutdown the app. Thoughts? Any internal mechanism I can call in native to have it "pretend" an issue occurred previously and force run BeforeSend/CrashedLastRun

I think the CrashedLastRun mechanism will ultimately be checking to see if there's an envelope for a crash report somewhere right? So that we could fake/mock?

[aritchie]

I think the CrashedLastRun mechanism will ultimately be checking to see if there's an envelope for a crash report somewhere right? So that we could fake/mock?

Can't really fake/mock the native layer though. This is smoke tested in the iOS sample app.

[aritchie]

This PR also now resolves #735 and #3944

[jamescrosswell]

Generally looking good.

I think we might be able to refactor the code dealing with the OnBeforeSend event into a BeforeSendWrapper, like what was done for Android. That would make it easier/possible to write unit tests for all of that logic (and prevent regressions in the future).