Use the test Makefile for all examples

* Rename and move sbysrc/demo[123].sby to docs/examples/demos
    * Make them use multiple tasks for multiple engines
* Scan docs/examples for sby files for make test
* `make ci` is now `NOSKIP` by default
* Skip scripts using `verific` w/o yosys verific support
    * This does not fail even with NOSKIP set

sbysrc/sby.py

@@ -381,6 +381,7 @@ if dump_taskinfo:
         taskinfo[taskname or ""] = {
             "mode": cfg.options.get("mode"),
             "engines": cfg.engines,
+            "script": cfg.script,
         }
     print(json.dumps(taskinfo, indent=2))
     sys.exit(0)