Introduce MSVC CI

[ppenzin]

Add MSVC CI jobs, testing on latest Windows VM image using provided build and test wrappers.

For #6547

[rhuanjl]

Hmm any obvious reason why the CI hasn't triggered here?

[ppenzin]

It failed parsing YAML. I got a little ahead of myself on the syntax after finding an example online :)

[ppenzin]

Finally. All follow up commits are just fixing mistakes in the initial one, we don't need to preserve their messages if testing succeeds.

I am assigning 5 parallel tasks to the CMake job and 5 to MSVC. We can try to combine them into one big job, it should yield faster builds, but at expense of readability.

[ppenzin]

For now, I am going to give 6 jobs to CMake (covering all needed) and the remaining 4 to Visual Studio, this should work as VS builds are much faster. I am also going to rebase all changes together.

[rhuanjl]

Looking at the speed comparisons - those windows builds are crazy fast.

Stand out differences:

1. the runtests.py testrunner prints a result for every test, the windows testrunner rl.exe only prints a summary and any failures
2. runtests.py seems to be running all tests 3 times with 3 different sets of flags, rl.exe appears to only do all the tests twice with 2 sets of flags

[ppenzin]

Maybe we should start with hiding the output - it produces enormous amount of text. If rl.exe cap number of concurrent tests it might also be the reason why it is faster.

[rhuanjl]

Maybe we should start with hiding the output - it produces enormous amount of text. If rl.exe cap number of concurrent tests it might also be the reason why it is faster.

Testing offline the excess output vanishes if runtests.py is called without a --logfile parameter - I don't want to open a PR because I'll delay your updates but two changes to try updating test/CMakeLists.txt with:

1. Remove --logfile ${CMAKE_BINARY_DIR}/check.log from the command? (This should drastically reduce the logging)
2. Add -j=4 to it to make it use 4 threads which is what the windows test runner does?

Edit: tried this and it didn't work. BUT a slight tweak to runtests.py did do it - see #6559

[ppenzin]

@Fly-Style I am going to merge, but will definitely address any feedback in a follow-up PR.