Add compiler warning check

Release notes

Add a CI job that checks for compiler warnings.

Details

@bwinter and I have fixed compiler warnings for a while in older CAFCore code. To make sure that new code doesn't introduce new warnings, I suggest to use a CI job. If the job fails, the rest of the pipeline runs until the end, but will eventually fail, see example here. If this causes any problems down the road, it is easy to disable the job.

This also removes the compile job with the DEBUG flag. I'm not sure what the purpose was and the output was virtually the same. If there was a good reason to have this job, I'm happy to re-enable it.