tools: add comprehensive coverage reporting to router check

[dschaller]

Description: add comprehensive coverage reporting to the router check tool.
Risk Level: Low
Testing: Added tests and manually tested
Docs Changes: Included
Release Notes: Included

[dschaller]

/wait

[dschaller]

/retest

[repokitteh-read-only]

🔨 rebuilding ci/circleci: clang_tidy (failed build)

🐱

Caused by: a #7865 (comment) was created by @dschaller.

see: more, trace.

[dschaller]

@dio @rgs1 @mattklein123 @jyotima mind taking a look at this? It’s an expansion off of #7727

[mattklein123]

Thanks good stuff, some small comments. It would pretty cool if there was some other way of tracking per-field coverage that was more built-in and less manual, but I can't think of anything.

/wait

[dschaller]

Yeah, I was hoping that it would be possible to make this less manual but couldn't think of anything that was promising. I'm especially not a fan of the vector of coverageFIelds but couldn't find an alternative.

On the plus side this increases visibility into what fields on routes are covered. 🎉

[mattklein123]

Thanks!

[jyotimahapatra]

#730