Correctly handle inlining of doc hidden foreign items
Fixes#123435.
In case a foreign item has doc(hidden) attribute, we simply merged its attributes with the re-export's, making it being removed once in the `strip_hidden` pass.
The solution was to use the same as for local reexported items: merge attributes, but not some of them (like `doc(hidden)`).
I originally checked if we could simply update `Item::is_doc_hidden` method to use `self.inline_stmt_id.is_some_and(|def_id| tcx.is_doc_hidden(def_id))` but unfortunately, it added (local) items that shouldn't be inlined. At least it unifies local and foreign items inlining, which I think is the best course of action here.
r? `@notriddle`
bcdc281e5c