Sanitize `ArrayElementAccess` in `IntermediateIntent`

[lethalgem]

Many tests are leaving ArrayElementAccess in the final intermediate intent. Although the final ii is solvable, not all ArrayElementAccesss are being removed.

Likely related to #528, though not confirmed yet

For example: non_const_index.yrt fails with

...
compiler internal error: array element access present in final intent exprs slotmap
@40..44: array element access present in final intent exprs slotmap

The test is below.

let n: int;
let a: int[10];

constraint a[n] == 3;

solve satisfy;

[mohammadfawaz]

This is fine now since the asm gen does support array accesses.