Block Editor: Prevent negative width values in Spacer block when used inside a row block

[himanshupathak95]

Fixes: #68847 (Point 1)

What?

Prevent negative width values in the Spacer block when used inside Row blocks.

Why?

Currently, when a Spacer block is placed in a Row block, it can accept negative width values, which is not ideal.

Testing Instructions

• Create or open a post/page
• Add a Row block
• Insert a Spacer block inside the Row
• Try to set a negative width value using the resize handle
• Verify that the minimum width remains at 0

Screencast

Before

Screen.Recording.2025-01-23.at.13.00.11.mov

After

Screen.Recording.2025-01-23.at.12.59.23.mov

[github-actions]

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Co-authored-by: himanshupathak95 <[email protected]>
Co-authored-by: yogeshbhutkar <[email protected]>

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