Corrects columns of Pull Requests in milestone projects

[Ryan089]

Summary

Edits previous workflow to place PR to the appropriate project column (In Progress / In Review) when it has been given a milestone. Previously PR's were placed in the Backlog column.

Changes to Files

Created custom action: determine-status-column
Edited workflow AddIssueToMilestoneProject

Limitations

I didn't go to the effort of checking whether the PR is open or not in this workflow. If essential functionality, I offer this as an exercise for an alternate contributor. My strong recommendation is just do not add milestones to PR's that are already closed (because: why would you need to do that??)

Fixes

Contributes to #1112 by completing the following task:

• When a GitHub Milestone is added to an open PR (develop repo):
  • if the PR has "WIP" in the title
    • add the PR to the GH Project of the same name as the Milestone, in the 'in progress' column
  • else
    • add the PR to the GH Project of the same name as the Milestone, in the 'in review' column

[cosmiccoincidence]

Code/files look good.

Obviously I cant test it until after it is merged though.

[cosmiccoincidence]

Tested. Works well. Good job!