Screenshots captured while emulation is paused don't get saved to disk until emulation is unpaused

[thekovic]

Describe the bug
Screenshots captured while emulation is paused don't get saved to disk until emulation is unpaused.

To Reproduce
Steps to reproduce the behavior:

1. Open any game.
2. Pause emulation using the Pause Emulation action.
3. Make a screenshot using the Capture Screenshot action.
4. Observe the screenshot not appearing in your Screenshots folder until emulation is unpaused using the Pause Emulation action again.

Expected behavior
Screenshot should get saved immediately despite emulation being paused.

[LukeUsher]

This is a side-effect of a deeper issue, see #1192
The emulator front-end is unable to get the state of a frame that has already occurred, so a screenshot is always of the frame 'after' you hit the button; when paused, no new frames are generated so the front-end doesn't get a chance to capture the display.