Fix for 2D viewport not updating in the editor when the camera moves

[radenling]

This fixes a problem with 2D viewports not taking the camera position into consideration when previewed in the editor.

This is based on the fix done in PR #40677 (which was never merged) with the addition of solving the problems mentioned in that review.

This will not not work for 3.x since queue_redraw() has changed name. I'll open a separate PR for the backported fix.

Fixes #40441