[ENHANCEMENT] Rework how FunkinGroup changes its children's variables

[MightyTheArmiddilo]

Description

When I first created FunkinGroup, I made it the way it was as I thought the way FlxNestedSprite did it was the only good way to do so. I found the local variables annoying, though, and so did other people I talked to that used it. So I decided to change that.

Now, in draw(), FunkinGroup saves the transformations of its children, applies new transformations like updateChildren() did, draws the children, and reapplies the original saved transformations. This allows for a similar functionality to be used without local variables.

Important

This PR is a breaking change for any mods that use FunkinGroup!! The main thing that mods would need to change would be localX -> x (and those alike). They may also need to change overrides of updateChildren() to positionChildren() or positionChild() or replace the setting of customChildUpdate with the setting of customChildPositioning

Note

While testing this PR, I noticed a bug with the clipRect implementation Kade made, where scale and angle would break the rendering. This isn't caused by this PR as I could cause it without this PR.