Replace deprecated KFilterDev::device with KCompressionDevice in KBlackBox

Summary:
KFilterDev::device is deprecated:

https://api.kde.org/frameworks/karchive/html/classKFilterDev.html

This patch replaces it with KCompressionDevice as recommended.

Test Plan:
1. Compile and install KBlackBox. No warnings about deprecation should be shown.
2. Run KBlackBox. The theme should be loaded as expected.

Reviewers: #kde_games, aacid

Reviewed By: aacid

Subscribers: kde-games-devel

Differential Revision: https://phabricator.kde.org/D23290