add tests that exercise communication with an actual driver

[lovasoa]

The CI config still needs tuning; opening the pr anyway in case you want to take on where I left off, @pacman82

[pacman82]

Remember, the issue which triggered this happend on linux / MacOS. It is not a strict requirement that this works on windows. It is fine if both for windows and iodbc only subset of tests run.

IMHO we do not need to test the full combination of every feature on every platform.

Hope this makes this simpler for you.

[lovasoa]

@pacman82 : I set up the full tests with drivers to run on windows macos and linux (using the the sqliteodbc driver). The vendored unixodbc feature is now fully tested on macos and linux. I'm quite happy with the result, and I'll feel more confident depending on it in sqlpage now that it's more extensively tested on ci.

I also included a quality of life improvement on macos that I discovered while setting this up. In unix-odbc/config.h we now set the necessary variables for the vendored unixodbc to discover brew-installed drivers automatically.

[pacman82]

Thanks. As said, I am a bit underwater at the moment. Yet, I'll take a closer look a it, once things cool down. Thanks for your contribution.

[lovasoa]

Hi @pacman82 ! Did you get the time to have a look at this ?

[pacman82]

Not, yet. Likely won't get a good look at it for another two weeks