ID Management: Improve speed of code used when creating/renaming and ID.

This commit affects `id_sort_by_name()` and `check_for_dupid()` helper:
* Add a new parameter, `ID *id_sorting_hint`, to `id_sort_by_name()`,
  and when non-NULL, check if we can insert `id` immediately before or
  after it. This can dramatically reduce time spent in that function.
* Use loop over whole list in `check_for_dupid()` to also define the
  likely ID pointer that will be neighbor with our new one.

This gives another decent speedup to all massive addition cases:

| Number and type of names of IDs  | old code | new code | speed improvement |
| -------------------------------- | -------- | -------- | ----------------- |
| 40K, mixed (14k rand, 26k const) |      39s |      33s |               18% |
| 40K, fully random                |      51s |      42s |               21% |
| 40K, fully constant              |      40s |      34s |               18% |

Combined with the previous commits, this makes massive addition of IDs more
than twice as fast as previously.

source/blender/windowmanager/intern/wm_files_link.c

@@ -828,7 +828,7 @@ static void lib_relocate_do(Main *bmain,
         BLI_strncpy(&old_id->name[len], "~000", 7);
       }
 
-      id_sort_by_name(which_libbase(bmain, GS(old_id->name)), old_id);
+      id_sort_by_name(which_libbase(bmain, GS(old_id->name)), old_id, NULL);
 
       BKE_reportf(
           reports,