Get the time it took to launch your application.

def app_start_up_time(self, package: str) -> str:
        '''Get the time it took to launch your application.'''
        output, _ = self._execute(
            '-s', self.device_sn, 'shell', 'am', 'start', '-W', package)
        return re.findall('TotalTime: \d+', output)[0]