Sentry .NET Enhanced stacktrace breaks on Mono

[bruno-garcia]

Path.GetFileName throws on Mono for "<2138123765123>" values, while on .net 5 doesn't throw.

https://github.com/getsentry/sentry-dotnet/blob/4e41189a211a4b60a20180edd3bfe113dc7030e3/src/Sentry/SentryOptions.cs#L446

Work around is to use StackTraceMode.Original for now (milestone 0.1.0)

But we can change the .NET SDK to special case <mvid> and not call Path.GetFileName or any other API that breaks. In a future milestone.

[semuserable]

Should this one be removed from 0.1.0 milestone?