Allow using complex type as array element type

[Y-Nak]

What is wrong?

Currently, array element types are restricted to primitive types.
Now, we can remove the restriction with the new codegen.

The test case below should be passed at least.

pub struct Pair {
    pub x: i32
    pub y: i32
}

contract Foo {
    pub fn static_sized_type_elem() -> Array<Pair, 2> {
        let pair1: Pair = Pair(x: 1, y: 2)
        let pair2: Pair = Pair(x: 10, y: 20)

        let arr: Array<Pair, 2> = [pair1, pair2]
        return arr
    }

    pub fn dynamic_sized_type_elem() -> Array<String<10>, u8>{
        let arr: Array<String<10>, 2> = ["Foo", "Bar"]
        return arr
    }
}

How can it be fixed

This can be fixed just by removing the restriction in the analyzer.
NOTE: It'd be better to wait for #729 to be merged because it will allow returning nested complex types.