Sync from experimental/unicode-collation

* tta/C/main/unicode-collation/collation_data_loader.h,
* tta/C/main/unicode-collation/collation_data_lookup.h:
rename and update.
* tta/C/main/unicode-collation/collation_data_loader.c,
* tta/C/main/unicode-collation/collation_data_lookup.c:
rename and update.

* tta/C/main/unicode-collation/collation_key.c,
* tta/C/main/unicode-collation/collation-table.c,
* tta/C/main/unicode-collation/collation_key.h: update.

* tta/C/main/manipulate_indices.c (get_sort_key) update calling code.