Added support for arrays as shader struct members

[Chaosus]

Allowed complex constructions like

shader_type canvas_item;

struct B {
	vec3 v;
	float k[1];
};

struct A
{
	float t[3];
	B b[2];
};

void fragment()
{
	A a = A( {0.0, 1.0, 0.0}, {B(vec3(1.0, 0.0, 1.0), {0.0}), B(vec3(0.0, 1.0, 0.0), {1.0})} );
	a.b[1].v[0] = 1.0;
	a.b[0] = B(vec3(1, 0, 1), {0.0});
	COLOR.rgb = a.b[0].v;
}

[Chaosus]

I think its working good, I will add fixes if any of bugs happen.