readOverlappingSegmentation API tweeks

[PaulHax]

Cherry on top suggestions for the Typescript API.

• For ReadOverlappingSegmentationResult, change segImage key to outputImage to match readImageDicomFileSeries https://github.com/Kitware/VolView/pull/653/files#diff-8c519b9691d63566a7ad7593c9510518e62018db910f8e007251cc17d32c25e4R201
• Consiter deleteing readSegmentation. I don't see use case for it when we have mergeSegments option in readOverlappingSegmentation. So if this is a go, actually just rename readOverlappingSegmentation -> readSegmentation.
• Remove stdout Row direction: 1 0 0, etc.
• Consiter upgrading metaInfo type for Typescript API: https://github.com/Kitware/VolView/pull/653/files#diff-8c519b9691d63566a7ad7593c9510518e62018db910f8e007251cc17d32c25e4R178-R191