Refactor Mega Evolution indicator sprite

[DizzyEggg]

Fixes #2404
Fixes #2368 (Doesn't really fix the issue, because in vanilla and expansion partner mons start with index 3, if that was changed then it's a problem with the hack)
Fixes #1984

Also fixes a plethora of issues with the current implementation of how Mega Evolution indicator sprite work. It was buggy as hell, you can set up a 2v2 battle with megas on each side, and the sprites can get really glitchy. I tried to fix it, but it was a mess so I decided to rewrite it from scratch.

The workflow of the indicators sprite is like this:

• load mega/omega/alpha indicators gfx at the start of the battle along with healthboxes gfx
• create 3 sets of sprites for each battler along with healthboxes sprites, but keep them all invisible
• visibility is toggled for 3 sprites whenever healthbox's visibility is changed or lvl value updated in the healthbox

Also:

• added mon cry to the primal/mega animation
• fixed an issue where partner's mega doesn't change into base species
• simplified VARIOUS for mega/primal
• made primal reversion anim also hide the healthbox similarly to mega evo animation
• Thanks to @Jaizu, Omega and Alpha indicator sprites use the same palette

[AsparagusEduardo]

• load mega/omega/alpha indicators gfx at the start of the battle along with healthboxes gfx
• create 3 sets of sprites for each battler along with healthboxes sprites, but keep them all invisible
• visibility is toggled for 3 sprites whenever healthbox's visibility is changed or lvl value updated in the healthbox

Oh. I wonder if this could cause issues for the Triple Battle branch Ghoul and I are working on.

[DizzyEggg]

• load mega/omega/alpha indicators gfx at the start of the battle along with healthboxes gfx
• create 3 sets of sprites for each battler along with healthboxes sprites, but keep them all invisible
• visibility is toggled for 3 sprites whenever healthbox's visibility is changed or lvl value updated in the healthbox

Oh. I wonder if this could cause issues for the Triple Battle branch Ghoul and I are working on.

It shouldn't, especially with the Omega and Alpha indicators palettes merged.

[AsparagusEduardo]

It shouldn't, especially with the Omega and Alpha indicators palettes merged.

Alright.