more usable minimizer output?

[Gankra]

When a test fails in the check step (so the test compiled and ran, but we didn't like the result we got out), we do a second pass, minimizing all the failures:

https://github.com/Gankra/abi-cafe/blob/6ba68656bd74d05692e3abb83a51a0bfc2b7ce32/src/main.rs#L242-L253

As a side-effect of building them we'll print out their paths, but we don't produce any summary:

https://github.com/Gankra/abi-cafe/blob/6ba68656bd74d05692e3abb83a51a0bfc2b7ce32/src/main.rs#L306-L309

We also, more importantly to me, don't actually produce a fully usable reproduction, we only produce two source files, and it's your problem to make use of them. In an ideal world we would generate a cargo and/or (C?)Make project you could build and run.

To that end at one point I tossed a "main.rs" in the harness includes, but I never sorted out the details. Honestly not sure what would be useful to people reporting/receiving bug reports.

https://github.com/Gankra/abi-cafe/blob/6ba68656bd74d05692e3abb83a51a0bfc2b7ce32/include/harness/main.rs#L1-L17

[Gankra]

I'm not sure if this can be part of abi-cafe proper but I would like the test failures to be easy to hang off of a github CI task as an artifacts zip