Add option to list failures when running in Passive mode

[mrlacey]

Is your feature request related to a problem? Please describe.

When running the command line version as part of a CI process on a large solution, finding the specific file(s) that has (have) failed often feels slow and frustrating.

Describe the solution you'd like

I'd like to add a --listfailures flag that, if passed (in combination with --passive), will list the failing files at the end of the output.

This way, I wouldn't have to search through the output to find the files that have failed. -- Computers are good at (better than me at) searching for and summarizing things, let's use that to make reviewing the output easier.

Describe alternatives you've considered

• Continue to do it manually: slow, error-prone, & frustrating.
• Add something separate in the CI to "process" the output to create the summary list: would leave more to manage and configure and may not be as flexible across platforms and CI platforms.

Additional context
Add any other context or screenshots about the feature request here.

None, but I'd be happy to implement it.

[mrlacey]

X-Ref #400

Maybe add 2 new options:
--listonlyfailures
and
--summarizefailures

will review further before proposing something more complete.