tests: Allow to specify which checks to run, in config.json
tests: Allow to specify which checks to run, in config.json

Usually for each different check you'll only want to run
that specific test while testing. But there are tests that are orthogonal
to checks and test clazy's infrastructure, for those tests it's
still useful to specify which checks to run.

nyalldawson/clazy,nyalldawson/clazy,nyalldawson/clazy,nyalldawson/clazy