Add HDR copy-desktop-to-clipboard functionality (Ctrl+P)

[Kaldaien]

This adds capturing the Windows desktop (using the display that SKIV is currently on) when Ctrl+P is pressed.

This is incomplete because the only way to trigger this functionality currently is with SKIV's window on screen, and people don't want a screenshot of SKIV (generally). I'm not clear how SKIF implemented hotkeys yet, so I leave this exercise up to you.

Additional functionality required:

1. Global hotkey (must be assignable)
2. Activate SKIV's window after the snapshot has completed (ideally, after the image finishes loading)
3. Optional modifier key to immediately enter snipping mode on the capture (viewer should switch to fullscreen before beginning a snip)