Add Freedesktop categories to Dopamine.desktop

[adem4ik]

On KDE, Dopamine currently appears under "Lost & Found" in the application menu. This happens because Dopamine.desktop only declares the Audio category, which is not enough on its own.

According to the Freedesktop Menu Specification, Audio is an additional category and requires the main category AudioVideo:

Desktop entry must include AudioVideo as well

This change:

• Adds the main category AudioVideo, so the entry is correctly classified as a multimedia application.
• Adds the additional category Player for finer-grained classification.

References:

• Main categories: https://dueno.pages.freedesktop.org/xdg-specs/menu-spec/latest/apa.html
• Additional categories: https://dueno.pages.freedesktop.org/xdg-specs/menu-spec/latest/apas02.html

P.S. After this is merged, it would be great if the same change could be reflected in the dopamine-official package on AUR, since it ships its own copy of Dopamine.desktop.

Screenshot:

[digimezzo]

Hi @adem4ik, thank you!