Global Styles: Fix incorrect usage of ItemGroup in the Background image panel

[im3dabasia]

Part of: #67425

What?

Revised <ItemGroup> to use role="none" and prevent it from rendering an unnecessary role="list" when it is not semantically required.

Why?

Avoids adding unwanted list roles where a semantic list is not necessary, ensuring accessibility standards are maintained without enforcing unnecessary constraints.

How?

Updated <ItemGroup> to include role="none" and an optional as prop for flexibility. By default ItemGroup renders a as a list which was generating the wrong markup. Which is not good for accessibility

Testing Instructions

1. Navigate to Appearance > Editor
2. Navigate to Global Styles > Background.
3. Inspect rendered Button labeled 'Add background image' and confirm they no longer include role="list" when unnecessary.
4. Validate that UI behavior and appearance remain unaffected.

Before	After

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