Update Japanese translation files (#1640)

* [l10n] ja: Improve Japanese Translations

* ja: about: Fix highlighting
* ja: Update Translations
* ja: Translate admin settings

Signed-off-by: lindwurm <lindwurm.q@gmail.com>

* Update ja.jsx

* Update doorkeeper.ja.yml

* Update ja.yml

* Update ja.jsx

* Update ja.jsx