[iOS] Add updates for LineHeight, TextDecorations, CharacterSpacing

[cat0363]

Description of Change

This PR fixes the problem that the LineHeight, TextDecorations, CharacterSpacing properties are not reflected when the label is displayed for the first time.

Called the MapFormatting method of LabelHandler in the MapFormatting method of Label.iOS.cs so that the values ​​of LineHeight, TextDecorations, and CharacterSpacing are reflected. I used a similar condition because LineHeight, TextDecorations, CharacterSpacing were updating only when the Text set on the Label was PlainText.

[src\Controls\src\Core\Label\Label.iOS.cs]

static void MapFormatting(ILabelHandler handler, Label label)
{
    handler.UpdateValue(nameof(ILabel.TextColor));
    handler.UpdateValue(nameof(ILabel.Font));

    if (!IsPlainText(label))
        return;

    LabelHandler.MapFormatting(handler, label);
}

Issues Fixed

Fixes #16204

Below is the execution result.

[ghost]

Hey there @cat0363! Thank you so much for your PR! Someone from the team will get assigned to your PR shortly and we'll get it reviewed.

[rmarinho]

/azp run

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