ACIR gen: Handle recursive ACIR calls

[vezenovm]

Problem

With the move to non-inlined ACIR calls we need to appropriately account for a program having multiple returns. Initial work for non-inlining ACIR was started here (AztecProtocol/aztec-packages#5341), however, it is missing recursive calls.

Happy Case

I should be able to recurse non-inlined ACIR functions.

Something like this should be feasible:

fn main(x: u32) {
    assert(fibonacci(x) == 8);
}

#[fold]
fn fibonacci(x: u32) -> u32 {
    if x <= 1 {
        x
    } else {
        fibonacci(x - 1) + fibonacci(x - 2)
    }
}

Project Impact

None

Impact Context

No response

Workaround

None

Workaround Description

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Additional Context

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