Allow update

[emahuni]

Describe the feature
Allow jobs to be updated. Sometimes we require to change a job's cron or something else without creating another job. Allow an update api on the job.

eg:

  const job = Cron('@daily', { name: 'eg'}, (job, ctx)=> console.log('do something...'))
  job.update('@weekly'); // change the cron job to a weekly instead of the initial daily
  job.update({name: 'Huga', catch: (e)=>console.log('heeee error what what...') }); // change cron job options

[emahuni]

please change the label from bug to feature request