2025-01-02

Collect link groups roots into set instead of list

Summary: This change is required for further diffs where we check each node in roots when traversing graph of linkables. We can do it with `list` too, but `set` is simply more perfromant.

Reviewed By: artempyanykh

Differential Revision: D67389696

fbshipit-source-id: a5ea7ace8693dc98b9c823d4453105a4005d0062