extensions/grunt/src/main.ts/findGruntCommand
async function findGruntCommand(rootPath: string): Promise<string> {
	let command: string;
	let platform = process.platform;
	if (platform === 'win32' && await exists(path.join(rootPath!, 'node_modules', '.bin', 'grunt.cmd'))) {
		command = path.join('.', 'node_modules', '.bin', 'grunt.cmd');
	} else if ((platform === 'linux' || platform === 'darwin') && await exists(path.join(rootPath!, 'node_modules', '.bin', 'grunt'))) {
		command = path.join('.', 'node_modules', '.bin', 'grunt');
	} else {
		command = 'grunt';
	}
	return command;
}