Fix shader incorrectly expects int on uint and vice-versa in cases

[Chaosus]

• Closes GDShader incorrectly expects int cases in switch on uint expressions #95453

This code will now compile correctly:

shader_type spatial;

const int iOne = 1;
const uint uOne = 1u;

void fragment() {
	
	int i; uint u;
	switch (i) {
		case iOne: break;
	}
	switch (u) {
		case uOne: break;
	}
}

Also, I've placed the case label duplication check code into case processing branch, the reason for that is that it will print an error at the case label itself:

Details

rather than

Details

Besides that, I've fixed a shader compiler failure when declaring a switch like this:

switch(1u) {
	default:
	break;

	case 1u:
	break;

	default:
	break;
}

[clayjohn]

Seems fine!

[akien-mga]

Thanks!