New Session status type `Unhandled`

[bitsandfoxes]

Description

Relevant docs PR https://github.com/getsentry/sentry-docs/pull/15086

The existing SessionEndStatus is to be extended by a new status Unhandled. This splits the session update after error capture https://github.com/getsentry/sentry-dotnet/blob/c57c0f284b8a9c6564bd56727a67a05ad0d51ba8/src/Sentry/SentryClient.cs#L364-L376

in two pieces:

• Exceptions that cause the application to crash
• Exceptions that do not cause a crash - i.e. through the UnobservedTaskExceptionIntegration or the Unity game engine

The Unhandled session end status is also terminal, meaning that the session updated as Unhandled is to be ended and not to receive further updates.

[linear[bot]]

NET-494