[CUE-5523] Fix Root file detection for multi-file OAS import#835

aman-v-singh wants to merge 2 commits intodeveloppostmanlabs/openapi-to-postman:developfrom

CUE-5523-multi-file-oas-import-assigning-root-to-the-wrong-filepostmanlabs/openapi-to-postman:CUE-5523-multi-file-oas-import-assigning-root-to-the-wrong-fileCopy head branch name to clipboard