Patch size grid artifact in segmentation mask output

Megaseg model patch size edges not being blended so grid artifacts present in output masks.

**How important is this feature to you? (Software team will re-prioritize all tickets based on current workload)**
high priority bug since it introduces artifacts in structure segmentation mask.

**Describe the solution you'd like**
Easiest thing would be to make a checkbox to set the patch size to the whole fov xyz dims so these artifacts go away. Could also work on optimizing the fusing/blending of edge overlap areas so that output segmentation masks don't have these artifacts.

**Additional context**
Add any other context or screenshots about the feature request here.