Add support for Enumerate Operator in IR conversion

When using the enumerate operator, the IR conversion tool throws an error.

Test case:
_fn f(input: u32[4]) -> u32 {
let result =
for ((i, elem), accum): ((u32, u32), u32) in **enumerate**(input) {
u32:0
}(u32:0);
u32:0
}_

Error:
For-loop is of an unsupported form for IR conversion; only a 'range(0, const)' call is supported, found non-range callee.

To execute: _ir_converter_main **\**_