Add support for adding Library Benefits to a screener

[prestoncabe]

As a Benefits Analyst
When I am on the Manage Benefits screen
Then I should be able to import from a library of pre-existing benefits to add to this screener
And still be able to create a new Custom Benefit from scratch if I so choose.

• imported benefits become a benefit like any other for the screener; they consist of library eligibility checks and the benefit's checks may be edited after import (including anything you could do for a "custom" benefit - add checks, remove checks, rename checks, associate custom checks)

In other words, an analyst can add Library Benefits or Custom Benefits to a screener. Both types of benefits behave the same after being added to a given screener.