Implement paste functionality in the blueprint graph

It’s a bit of a serious oversight. If you’re using Synergy to control a Mac there’s no way to copy and paste besides right-clicking. And we know what that means: there’s no way to paste because right click is… bizarre in blueprint graphs. There is literally not a single Paste option in any menu. So:

  1. Please fix the keyboard command detection on Mac to be more consistent
  2. Please implement standard UI features like an Edit menu that has copy and paste in it.