Implement UDIM Atlas

[ucupumar]

Implement UDIM Atlas to get around the even smaller texture limit of UDIM (27 for Nvidia, 12 for Radeon)

• [x] New UDIM atlas segment
• [x] Refresh UDIM atlas segments based on new UV islands
• [x] Delete UDIM atlas segment
• [x] Convert to standard UDIM and vice versa
• [x] Duplicate UDIM atlas segment
• [x] Bake to UDIM Atlas segment layer / mask
• [x] Bake mask to UDIM atlas segment
• [x] Merge to UDIM atlas segment
• [x] Transfer UV on UDIM atlas segment
• [x] Auto create new UDIM atlas image if new segment not fit when refreshing UDIM atlas segments based on new UV islands