zig fmt: Fix formatting of if expressions

[87flowers]

This fixes some issues with zig fmt and if expressions.

Sometimes when formatting an if expression, the renderer does not carry on with the correct indentation until the end of the if expression. See examples below.

Before PR

test {
    const foo =
        if (1 == 2)
        1
    else if (3 > 4)
        2
    else
        0;

    const foo, const bar =
        if (1 == 2)
        .{ 0, 0 }
    else if (3 > 4)
        .{ 1, 1 }
    else
        .{ 2, 2 };

    const foo = 1 +
        if (1 == 2)
        2
    else
        0;

    errval catch |e|
        if (e == error.Meow)
        return 69
    else
        unreachable;

    return if (1 == 2)
        1
    else if (3 > 4)
        2
    else
        0;
}

After PR

test {
    const foo =
        if (1 == 2)
            1
        else if (3 > 4)
            2
        else
            0;

    const foo, const bar =
        if (1 == 2)
            .{ 0, 0 }
        else if (3 > 4)
            .{ 1, 1 }
        else
            .{ 2, 2 };

    const foo = 1 +
            if (1 == 2)
                2
            else
                0;

    errval catch |e|
        if (e == error.Meow)
            return 69
        else
            unreachable;

    return if (1 == 2)
        1
    else if (3 > 4)
        2
    else
        0;
}

[castholm]

Unfortunately, while this fix solves some erroneous cases, it also introduces new ones:

// before
const foo = 1 + if (1 == 2)
    2
else
    0;

const bar = 100 + calculate(
    200,
    300,
);

// after
const foo = 1 + if (1 == 2)
        2
    else
        0;

const bar = 100 + calculate(
        200,
        300,
    );

I have briefely looked into fixing this issue with zig fmt in the past and I believe the problem with the indentation of if-else expressions goes deeper than what can be easily fixed by adjusting some ais.pushIndent/popIndent calls. A proper fix would likely require a complete rethinking and rewrite of the way indentation is tracked and handled by the renderer.

[87flowers]

Many thanks, I'll take a deeper look at this and revisit at a later date.