Motivation for this change

The main motivation for this change was to add actual icons to Rambox Pro since the lack of any icons was bugging me and no doubt any other users of the package.

I have also resolved an issue where the Electron application itself was autostarted at login instead of Rambox Pro like it should be.

I also decided to clean up the directory structure in-line with other similar packages.

Things done

• Tested using sandboxing (nix.useSandbox on NixOS, or option sandbox in nix.conf on non-NixOS linux)
• Built on platform(s)
  • NixOS
  • macOS
  • other Linux distributions
• Tested via one or more NixOS test(s) if existing and applicable for the change (look inside nixos/tests)
• Tested compilation of all pkgs that depend on this change using nix-shell -p nix-review --run "nix-review wip"
• Tested execution of all binary files (usually in ./result/bin/)
• Determined the impact on package closure size (by running nix path-info -S before and after)
• Ensured that relevant documentation is up to date
• Fits CONTRIBUTING.md.

Notify maintainers

cc @