Handle Exceptions thrown during discovery, such as in Custom Attributes

[manfred-brands]

Fixes #4096
Fixes #4107

Tests with Exceptions are Marked As Invalid and show up as an Error.
Fixtures with Exceptions are non-runnable and don't show up with dotnet test.

One alternative option would be to make a special fixture with one runable method that fails.

[stevenaw]

Thanks @manfred-brands ! Great that this could be fixed so simply.
Two minor nitpicks/ suggestions. I also would appreciate a second review from someone else

[manfred-brands]

Thanks @stevenaw, changes made.

[stevenaw]

Very cool, thanks @manfred-brands ! Looks great to me 👍

[manfred-brands]

Is there anything blocking this from being merged in?

[stevenaw]

@manfred-brands I'd been hoping to get a second pair of eyes on it since this is a part of the codebase I'm less familiar with, but perhaps it could also be merged as-is.
@mikkelbu @rprouse are either of you available to do a review?

[mikkelbu]

I'm sorry. This PR got lost in too many GitHub notifications. I'll take a look at this today or tomorrow

[rprouse]

Sorry for the delay. This looks good. For anyone else reviewing, ignore whitespace, it is much easier to read.

[mikkelbu]

LGTM. I've only some very minor comments 👍

[manfred-brands]

Cherry pick into master depends on #4053

[manfred-brands]

This is ready for merge into v3.13-dev now.

[stevenaw]

Thanks @manfred-brands ! LGTM 🎉