fix(expand): output safety comment before statements

[asterite]

Description

Problem

Resolves #8371

Summary

Now safety comments will always be added before statements, never in the middle of expressions.

For this program:

global G_A: [u16; 3] = [33700, 47314, 35095];
global G_B: [u16; 3] = [59890, 17417, 14409];
fn main(a: [u16; 3], b: [bool; 1]) -> pub bool {
    // Safety: testing context
    if unsafe { func_1(G_B, true) }[(((a[0] as u32) % (G_B[2] as u32)) % 1)] {
        // Safety: testing context
        let c = unsafe { func_1(a, b[0]) };
        b[0]
    } else {
        ((a[((a[0] as u32) % 3)] as u32) > ((24993 % G_A[1]) as u32))
    }
}
unconstrained fn func_1(a: [u16; 3], b: bool) -> [bool; 1] {
    [false]
}

the output of nargo expand is now:

global G_A: [u16; 3] = [33700, 47314, 35095];

global G_B: [u16; 3] = [59890, 17417, 14409];

fn main(a: [u16; 3], b: [bool; 1]) -> pub bool {
    // Safety: comment added by `nargo expand`
    if unsafe { func_1(G_B, true) }[((a[0] as u32) % (G_B[2] as u32)) % 1] {
        // Safety: comment added by `nargo expand`
        let c: [bool; 1] = unsafe { func_1(a, b[0]) };
        b[0]
    } else {
        (a[(a[0] as u32) % 3] as u32) > ((24993 % G_A[1]) as u32)
    }
}

unconstrained fn func_1(a: [u16; 3], b: bool) -> [bool; 1] {
    [false]
}

Additional Context

In a next PR I'll try to preserve safety comments in the AST so we can output those instead of a generated comment.

Documentation

Check one:

• No documentation needed.
• Documentation included in this PR.
• [For Experimental Features] Documentation to be submitted in a separate PR.

PR Checklist

• I have tested the changes locally.
• I have formatted the changes with Prettier and/or cargo fmt on default settings.

[vezenovm]

Awesome thanks!