Blender Git Loki

Disable interpolation of customdata layers on edge slide

This option might be useful in some cases like keeping UV coordinated in kind of
"correct" state so sliding edge loop will also slide edges in UV. But for other
layers like shapekeys and vertex colors it's arguable it's actually needed.

The way it's currently done isn't actually acceptable because it doesn't take
flags like UVCALC_TRANSFORM_CORRECT into account and also makes extra unwanted
things like interpolating shapekeys which leads to propagating changes into
basis keys and also results with slide applied twice for relative keys because
offset is also applying on loading edit mesh.

Also discussed with Brecht who agreed with marking this things as TODO and
disabling for now.

This should fix issue reported in #30387: Edge Slide propogates to Basis Shape Key