Copy inventory as part of validate host

We are collcting information about the running zuul system in
validate-host. Move the inventory collection here with the rest of
it. Also, put it in zuul-info. It's debugging info about the ansible
layer.

Change-Id: I5dded8f3545e725cbc11c1eae194857fe9623ab1

roles/validate-host/tasks/main.yaml

@@ -30,3 +30,9 @@
   template:
     dest: "{{ zuul_info_dir }}/zuul-info.{{ inventory_hostname }}.txt"
     src: templates/zuul-info.j2
+
+- name: Copy ansible inventory to logs dir
+  delegate_to: localhost
+  copy:
+    src: "{{ inventory_file }}"
+    dest: "{{ zuul_info_dir }}"