cosmic: add target

[oomfiee]

i would like to see stylix supporting cosmic desktop in the near future.

[danth]

This most likely depends on the relevant module in NixOS being completed.

Tracking issue: NixOS/nixpkgs#259641
PR for NixOS module: NixOS/nixpkgs#292601

[HeitorAugustoLN]

cosmic-manager might be useful for this.

[cramt]

the cosmic module has just been merged in nixos NixOS/nixpkgs#392837

[HeitorAugustoLN]

Just an update, I have upstreamed the core modules and lib from cosmic-manager to home-manager and nixpkgs. As soon as they get merged, I will probably work on this target.

• cosmic: add module home-manager#7812
• lib.ron: init NixOS/nixpkgs#440544
• RON Types NixOS/nixpkgs#442207
• nixos/cosmic: add declarative settings support NixOS/nixpkgs#440803