change layout for better management

- instead of just `syspkgs` and `srcpkgs` add more lists
  - `appimages`, `flatpkgs` and others as they come up

vars/neovim.yml

@@ -1,7 +1,7 @@
 # vim: set filetype=yaml.ansible :
 ---
 version: v0.10.3
-install_prefix: "{{ default_config.install_prefix }}"
+install_prefix: "{{ default_install_prefix }}"
 install_dir: /opt/nvim
 use_appimage: true
 use_syspkg: true