fix: Return `parent` as numeric vector in `bfs()` and `dfs()` instead of `igraph.vs`#2455

Copilot wants to merge 3 commits intomainigraph/rigraph:mainfrom

copilot/fix-bfs-dfs-father-nasigraph/rigraph:copilot/fix-bfs-dfs-father-nasCopy head branch name to clipboard