[Coral-Schema] handle single-element unions when the supplied column schema does not specify <uniontype>#557

ruolin59 wants to merge 5 commits intolinkedin:masterlinkedin/coral:masterfrom

ruolin59:ruolin/fix-array-and-map-union-extractionruolin59/coral:ruolin/fix-array-and-map-union-extractionCopy head branch name to clipboard