Fix cursor editor icon width calculation for proper DPI scaling

[SimonZhao888]

Fixes #14167

Root Cause

Icons similar to HSplit.cur, VSplit.cur are wider than other icons at certain DPI settings (such as 125%, 175%， 225%， 250%), which is causing the webtable to display abnormally.

Proposed changes

• Modify the drawing method for list items to use the default icon width as a reference, ensuring that all icons are the same size.

Customer Impact

• Cursor editor items are displayed correctly in propertyGrid with all DPI settings.

Regression?

• No

Risk

• Minimal

Screenshots

Before

After

150DPI:

150DPI.mp4

175DPI:

175DPI.mp4

200DPI:

200DPI.mp4

225DPI:

225DPI.mp4

Test methodology

• Manually

Test environment(s)

• 11.0.0-alpha.1.25619.109

Microsoft Reviewers: Open in CodeFlow

Microsoft Reviewers: Open in CodeFlow

[SimonZhao888]

Here is another issue: when the DPI is set to 125%, 175%, 225%, 250%, the .cur icon exhibits an icon offset problem.
Normal：

Offset：

[Copilot]

Pull request overview

This PR updates CursorEditor.CursorUI drawing to use a uniform cursor icon width, aiming to fix cursor editor item layout at fractional DPI settings in the PropertyGrid.

Changes:

• Adds a cached _cursorWidth based on the scaled default cursor icon.
• Updates owner-drawn cursor list items to use that uniform width for the icon box, cursor drawing, and text offset.

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