Add "draft" and "merged" flags to GitHub pack's Pull Request sync

I have a use case where I’m wanting to take certain actions upon Pull Requests from GitHub within Coda based on a representation of their state.

The pack provides the “state” column, which is either “open” or “closed”, but without the “draft” and “merged” flags that GitHub’s API provides, it’s not possible to determine whether an “open” PR has been opened or is in a draft state or whether a “closed” PR has been closed or merged.

My mistake, there is an “IsMerged” field that covers the “merged” flag, but an “IsDraft” flag would be super handy.