[4.5-beta1] Custom mouse cursor images not working in embedded game window on macOS

[mertkasar]

Tested versions

• Reproducible in: v4.5.beta1.official [46c495c], v4.5.dev5.official [64b0990], v4.5.dev4.official [209a446]
• Reproducible only on macOS

System information

Godot v4.5.beta1 - macOS Sequoia (15.5.0) - Multi-window, 2 monitors - Metal (Forward+) - integrated Apple M1 Pro (Apple7) - Apple M1 Pro (10 threads) - 16.00 GiB memory

Issue description

Embedded game window does not respect the custom mouse cursor image set either in code or in project settings. It works fine in non-embedded game windows.

Follow-up issue for #107819

Steps to reproduce

• Open the MRP
• Make sure "Embed game on next play" is on (floating or not)
• Observe custom cursor image is not showing up as it does with "Embed game on next play" is off

Minimal reproduction project (MRP)

mrp-embed-custom-cursor.zip

[akien-mga]

CC @stuartcarnie