[BE] Item timing config option

[MandL27]

Explanation

In gens 1-3, using an item in battle consumes it and applies its effects immediately, and isn't undoable in doubles. In gens 4+, using an item in battle is queued like move selection and run at a similar (needs testing) priority to switching out. A barebones implementation could play the same sound with no animation (as is done for AI item use), but a more robust version would involve...

Item use animation

This is a clusterfuck. Gen 4 added a "used item" animation for the player's side only, involving (in Emerald terms) the ThinRingExpandingSprite part of held items (with its new SE), followed by HealingEffect overlaid on a silent StatusClearedEffect. Gens 5+ apply this animation to the enemy side as well, and move the second half into its own "HP restored" animation that plays whenever a mon heals. This also led to HealingEffect and StatusClearedEffect being removed from any move animations that used them. The most flexible solution here is to use per-gen constants, but that'd still create tons of breaking changes on move anims.