Bug 21351: Rename the Taiwanese language pack to use correct file name

Bug 21351: Rename the Taiwanese language pack to use correct file name

The words "Han (Simplified variant)" is appearing in the language name because the file is titled "zh-Hans-TW" when it should be titled "zh-Hant-TW". The database is set up to use "Hant" but it just incorrectly named.

Test plan
1. Apply patch.
2. Install zh-Hant-TW on your Koha server.
3. Navagate to I18N/L10N preferences and confirm that the english text description states (Traditional variant).

Signed-off-by: Katrin Fischer <katrin.fischer.83@web.de>
Files on translate.kc.org have already been fixed by Bernardo.
Signed-off-by: Chris Cormack <chrisc@catalyst.net.nz>
Signed-off-by: Nick Clemens <nick@bywatersolutions.com>