Add the capability to generate a dump file for unhandled exceptions in asp.net core applications.

.net core supports generating core dumps when an application crashes as a result of unhandled exceptions (https://github.com/dotnet/coreclr/blob/master/Documentation/botr/xplat-minidump-generation.md). This does not however work for asp.net core as unhandled exceptions (from a users code perspective) are handled down the stack. There should be a mechanism by which I can enable core dump generation in asp.net core applications.