Cleanup: VFont: Move to IDTypeInfo and remove unused BKE API

This was particularly strange because we had a _free_data() function.
But still the one I replaced was of course the _free() one.

And we should rename the _free_data_ function later to avoid confusions.

source/blender/blenkernel/intern/lib_id_delete.c

@@ -184,7 +184,7 @@ void BKE_libblock_free_datablock(ID *id, const int UNUSED(flag))
       BLI_assert(0);
       break;
     case ID_VF:
-      BKE_vfont_free((VFont *)id);
+      BLI_assert(0);
       break;
     case ID_TXT:
       BLI_assert(0);