[4.5] Fix FileDialog icon scale in editor

[BLumia]

This PR backport #114035

In Godot 4.5.1, on HiDPI screen, the file dialog triggered from "Manage export template" > "Install from file" have the same issue that 144035 attempts to address:

Thus I did this backport:

[AThousandShips]

I'd say this should have a co-author for KoBeWi as this is just a back port of that code

[BLumia]

I'd say this should have a co-author for KoBeWi as this is just a back port of that code

Ah sorry I completely forgot to do that! Patch updated, hope I get it right this time.

[KoBeWi]

The problem is that the template manager uses FileDialog, while everything in editor should be using EditorFileDialog, which doesn't have this problem.
Although the issue affects user plugins I guess.

[BLumia]

The two failing checks caused by network issue might need to be retriggered manually.

[akien-mga]

Thanks!