Fix HUD scissors being out of bounds

[Wyvest]

causes crashes on versions 1.21.10 and above, causes visual glitches on versions below

crash in question: https://haste.prod.getfire.bot/t48mc95yaxqy

[decce6]

Thanks for the contribution, but could you clarify how to reproduce the crash / the visual glitches?

Looks like there's a chance this will also resolve #115

[Wyvest]

could you clarify how to reproduce the crash / the visual glitches

1. turn on gnetum hud downscaling, set gui scale to 2 or higher
2. install vanillahud
3. join any server and open tab
4. the tab animation, which uses a scissor to animate, will crash minecraft

alternatively, I did this on the gnetum repo to temporarily reproduce the issue
in HudMixin.gnetum$wrapHudRender, right after Gnetum.rendering = true;:

var prev = Gnetum.currentElement;
Gnetum.currentElement = Gnetum.config.map.get("hotbar");
guiGraphics.enableScissor(0, 0, 100, 50);
guiGraphics.fill(0, 0, 400, 400, 0x80FF0000);
guiGraphics.disableScissor();
Gnetum.currentElement = prev;