Break into debugger on assertion failures (dotnet/coreclr#19702)

Break into debugger on assertion failures (dotnet/coreclr#19702)

* Break into debugger on assertion failures

Assertion failures terminated the process by default that made them hard to debug. Changed them to
break into debugger or trigger fail fast when the debugger is not attached. This should make the day-to-day
CoreCLR developer experience better and it is simular to what we had on .NET Framework in the past.

* Fix Unix build break

Add RaiseFailFastException to Unix PAL

Commit migrated from https://github.com/dotnet/coreclr/commit/5e83757c500f9c26cac8da254e0fe9e3a7580390