Add ref to array() and object() of JSONValue getters to add new element

[repeatedly]

Continuation of #1421

New JSONValue API can't add new element to array or object directly.
Making array / object getter ref return fuction fix this problem.

[ghost]

Please add test-cases.

[repeatedly]

@AndrejMitrovic added

[ghost]

So essentially for the array case this depends on the following behavior:

import std.stdio;

struct S
{
    /// getter
    @property ref int[] array()
    {
        writeln("getter");
        return _array;
    }

    /// setter
    @property int[] array(int[] v)
    {
        writeln("setter");
        return _array;
    }

    int[] _array;
}

void main()
{
    S s;
    s.array = [1];   // calls setter
    s.array ~= [1];  // calls getter
}

I'm not sure whether this is appropriate or whether we should use operator overloading here? What do others think, @9rnsr, @CyberShadow ?

I think the code is still correct though, since the getter does type checking anyway.

[CyberShadow]

It looks fine on the surface. One potential issue is that it does not allow building an array from zero, as the first append will call the getter, but that's not different from the equivalent JavaScript code (arr.push(value) when arr is undefined).

[9rnsr]

Looks good to me.

[9rnsr]

Auto-merge toggled on

[9rnsr]

I think the fixed issue is a regression introduced in the 2.065 development.
https://d.puremagic.com/issues/show_bug.cgi?id=12168

So I think we should cherry-pick it in 2.065 release branch.