Add warnings for incompatible options

[spikespaz]

• When config attributes are unspecified, but HM-generated config is required for other options.
  • Also add option to turn off managed config, or disable if no options are used.
  • Currently the config is always generated whenever cfg.enable is true.
  • https://github.com/hyprwm/Hyprland/blob/299d201e562c0d0d1530d1559ff33802a1470815/nix/hm-module.nix#L109C15-L118