Debian packages: stuff (trunk)

Gamescope 3.16b (latest; incl. polaris-gpu-fix)
mesa 25 (latest, as tar; + -dev-packages as seperate tar)
Breeze Enhanced (Plasma 6.1, currently not working on 6.3)
Kvantum (Plasma 6.2+)
Klassy (Plasma 6.21+)
Kiview