As demonstrated in WT-6412, multiple code paths call __wt_hs_cursor_position all of which then do their own traversal in a separate loop, it we be good if we could somehow merge their logic into a single function.

The PR for WT-6412 is the best place to start looking at this, in order to handle all the callers independently several new checks were added for globally visible tombstones, ideally we'd like that check to happen in the new function, or an updated __wt_hs_cursor_position.