[feature request] support job template

[xiaohui-zhangxh]

Hi, I'm deploying Ruby on Rails app with this chart, it requires running db migration to make sure db is up to date, usually I can define a Helm hook to start a job to update db.

This is an article describes how to deploy Rails app to K8s https://engineering.adwerx.com/rails-on-kubernetes-8cd4940eacbe , so I think most Rails apps need a job hook defined, can we add this feature to component-chart?