Blender Git Loki

Fix T92494: Node Editor dot grid not respecting display resolution scale

This seems wrong and was especially noticeable since transform snapping
does account for it (which was reported in T92494).
Now divide the `DotGridLevelInfo` `step_factor` by the default of 20 for
`U.widget_unit` and scale it later by the actual interface scale.

note: when zooming, this will still always snap to the smallest dot
level (not sure, with a bit more work it could be possible to only snap
to the lowest visible level after fading?)

Maniphest Tasks: T92494

Differential Revision: https://developer.blender.org/D13002