Remove compiler and cpp_std from `build-yosys` matrix. Using `config-$CC` will instead fall back to default values.
Drop `Tool versions` step and introduce `yosys-config` output instead.
Rename `test-builds` to `test-compile`.
`os_name` in include section needs to be explicit (putting it at the end doesn't
apply to the extra jobs).
Move macOS test to extra job instead of doing all gcc/clang (which isn't setup
for mac anyway).
Also adds name to build-yosys task.
Krystine Sherwin