restructuring for easier maintenance

- creating src packages when things can't be installed via
  actual system package
- neovim srcpkg is being worked on now

tasks/pkgs/Darwin/carapace.yml

@@ -0,0 +1,9 @@
+---
+- name: append carapace to brewpkgs
+  set_fact:
+    brewpkgs: "{{ brewpkgs + [ 'carapace' ] }}"
+  tags:
+    - MacOS
+    - homebrew
+    - package
+    - nushell