bspwm module: refactor

[ericsagnes]

Motivation for this change

Make bspwm module more "standard", and avoid duplication of code.

Contents:

• removal of bspwm-unstable module in favor of services.xserver.windowManager.bspwm.package
• new options:
  • bspwm.package to select which bspwm package to use
  • bspwm.configFile to set the bspwm configuration file
  • bspwm.sxhkd.package to select which sxhkd package to use
  • bspwm.sxhkd.configFile to set the sxhkd configuration file
• removal of startThroughSession and sessionScript options as ${pkgs.bspwm}/bin/bspwm-session does not exists anymore

cc @cedeel @Adjective-Object

Things done

• Tested using sandboxing
  (nix.useSandbox on NixOS,
  or option build-use-sandbox in nix.conf
  on non-NixOS)
• Built on platform(s)
  • NixOS
  • macOS
  • Linux
• Tested compilation of all pkgs that depend on this change using nix-shell -p nox --run "nox-review wip"
• Tested execution of all binary files (usually in ./result/bin/)
• Fits CONTRIBUTING.md.

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[mention-bot]

@ericsagnes, thanks for your PR! By analyzing the history of the files in this pull request, we identified @cedeel, @Adjective-Object and @meisternu to be potential reviewers.

[ericsagnes]

Thanks for merging!