Blender Git Loki

UV: Increment snapping based on new UV grid types

Since the default UV editor grid has been replaced with a new
subdividing grid and dynamic grid (T78389) has also been implemented,
increment snapping value needs to change according to the grid
configuration in use.

This commit ensures that the increment snapping value is changed
according to the grid dimensions currently in use.
Example - For a NxN grid the increment value is set as 1/N