Fix Palette Properties Dialog Accessibility

[shubham-shinde-442]

Resolves: #18880

I believe these changes improve the accessibility of this dialog to some extent, except for the spin box.

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[cbjeukendrup]

It should be possible to do it for the spinboxes as well. Of course, that's slightly more complicated because they are in a Repeater, but that's easy to solve: you can use model.index to get the index.
So, you would do

IncrementalPropertyControl {
    …
    navigation.panel: navigationPanel
    navigation.order: 2 + model.index
    navigation.accessible.name: modelData["title"]
    …
}

    // And then in some control below…
    navigation.order: 2 + repeater.count

[shubham-shinde-442]

Thanks for the suggestion @cbjeukendrup. I tried this approach earlier, but after navigating to the first spin box (i.e. Width), it's not possible to navigate to the other spin boxes using the arrow keys, which leads to issue #20515

[cbjeukendrup]

As a workaround, one can use the left/right arrows instead of up/down, and sometimes one needs to press Esc to be able to move to the next one.
Since this is the case for all spin boxes currently in the app, I think it is preferable to add navigation support to those in this dialog too; then, when #20515 etc. are fixed, it will work automatically for this dialog too.
(Otherwise, if we don't add navigation support for those spin boxes now, it is annoying that we have to remember to do it later. And having them keyboard-accessible in some way is better than in no way at all.)

[shubham-shinde-442]

@cbjeukendrup Ok, Updated.

[cbjeukendrup]

Shouldn't we set the order too, so that it doesn't collide with the navigationPanel of the other items?

[cbjeukendrup]

I found that the "palette cell properties" dialog (right-click on a specific palette cell to find it) also doesn't have navigation yet. Since that dialog is so similar, it might make sense to fix that one too in this PR.