Remove compiler and cpp_std from `build-yosys` matrix. Using `config-$CC` will instead fall back to default values. Drop `Tool versions` step and introduce `yosys-config` output instead. Rename `test-builds` to `test-compile`.
Remove compiler and cpp_std from `build-yosys` matrix. Using `config-$CC` will instead fall back to default values. Drop `Tool versions` step and introduce `yosys-config` output instead. Rename `test-builds` to `test-compile`.