
This switches to `makeIntrusiveRefCnt<FileSystem>` where creating a new object, and to passing/returning by `IntrusiveRefCntPtr<FileSystem>` instead of `FileSystem*` or `FileSystem&`, when dealing with existing objects. Part of cleanup #151026.
This switches to `makeIntrusiveRefCnt<FileSystem>` where creating a new object, and to passing/returning by `IntrusiveRefCntPtr<FileSystem>` instead of `FileSystem*` or `FileSystem&`, when dealing with existing objects. Part of cleanup #151026.