separate expiry for deployment plans

This enhancement request is to be able to control the expiry of Deployment plans
including failed Deployment plans.

Currently we can control the expiry of Build/Deployment plans using a global setting
or on a Plan specific level. We can also set the minimum number of successful deployment
plans to keep.

We would like to be able to have different expiry rules for Deployment plans.
We would like to retain failed Deployment plans. Not just successful ones.