Implement idle animations

[olanti-p]

Purpose of change

Implement idle animations.
Turns out UDP already has a bunch of them (e.g. for spore clouds), but they went unused as BN lacks relevant code.

Describe the solution

Cherry-picked CleverRaven#40342, then heavily modified it:

1. Made the code request redraws if there are idle animations on screen (required due to changes from Don't redraw if animations are enabled, but there is nothing to animate #451).
2. If animations are disabled, fall back to showing the first frame of the animation (instead of random frame).
3. Added random stagger to trap/item animations to make them look nicer.

Testing

Tested with UDP on:

1. spore clouds and 'Spore dusted' status effect
2. lit torches, both wielded and dropped
3. dissectors

CPU usage stays at ≤1% when none of those are visible, and at ≈8% otherwise.
When animations are disabled, all monsters/items use same tile (and CPU remains at ≤1%).

Additional context

[Proxiehunter]

I was wondering why Bright Nights didn't seem to have this feature I've seen in Rycon and Vormithrax's vids. Hopefully this build will be available soon.