Fix exit code of --help and --version, and test them in CI

Corrects prior regression which caused ERROR output and exit code of 1.

platform/windows/godot_windows.cpp

@@ -166,6 +166,10 @@ int widechar_main(int argc, wchar_t **argv) {
 			delete[] argv_utf8[i];
 		}
 		delete[] argv_utf8;
+
+		if (err == ERR_HELP) { // Returned by --help and --version, so success.
+			return 0;
+		}
 		return 255;
 	}